Python ast.Call() Examples

def visit_Expr(self, node):
        newnode = ast.copy_location(ast.Expr(
                value = ast.Call(
                    func = ast.Attribute(
                        value = ast.Name(id='__swirlypy_recorder__',
                                    ctx=ast.Load()),
                                    attr="record",
                                    ctx=ast.Load()),
                                    args=[node.value],
                                    keywords=[],
                                    starargs=None,
                                    kwargs=None
                        )
                    ),
                node)
        ast.fix_missing_locations(newnode)
        return newnode 

def compile_expression(exp):
    cached = cache.get(exp)
    if cached is not None:
        return cached
    _exp = ast.parse(exp)
    nodes = [node for node in ast.walk(_exp)]
    if len(nodes) < 2 or not isinstance(nodes[1], ast.Expr):
        raise ExpressionError("%s is not Expression" % exp)
    for node in nodes:
        if isinstance(node, ast.Call):
            raise ExpressionError("Call method is forbidden")
        if isinstance(node, ast.Lambda):
            raise ExpressionError("Lambda is strongly forbidden")
    result = compile(exp, '<string>', mode='eval')
    cache[exp] = result
    return result 

def pre_Assign(self):
        value = self.cur_node.value
        for target in self.cur_node.targets:
            # ignore Subscripts for now
            if isinstance(target, _ast.Name):
                if target.id == '_target_model':
                    assert(isinstance(value, _ast.Call))
                    # done in three separate phases for safety with stringly-typed arguments
                    StateSpaceLabelWalker(value.args[0])
                    LabelWalker(value.args[1])
                    ExpressionWalker(value.args[2])
                else:
                    LabelWalker(value)

                # Build dependencies from the rhs
                # We don't consider the function name a dependency so bypass that
                critical_ast = value.args if isinstance(value, _ast.Call) else value
                value._dependencies = DependencyWalker(critical_ast).dependencies
                self.upgrades[target.id] = value

        return False


# Build variables for filling in the template 

def visit_BoolOp(self, node, **kwargs):
        def visitor(x, y):
            lhs = self._try_visit_binop(x)
            rhs = self._try_visit_binop(y)

            op, op_class, lhs, rhs = self._maybe_transform_eq_ne(
                node, lhs, rhs)
            return self._maybe_evaluate_binop(op, node.op, lhs, rhs)

        operands = node.values
        return reduce(visitor, operands)


# ast.Call signature changed on 3.5,
# conditionally change which methods is named
# visit_Call depending on Python version, #11097 

def visit_With(self, node):
        parallel_tasks = []
        if len(node.items) > 1:
            raise ValueError(
                "Only a single context is supported in 'with' statements inside the action."
            )
        context = eval(
            compile(ast.Expression(node.items[0].context_expr), "", "eval"),
            self._globals,
        )
        if context.__calm_type__ == "parallel":
            for statement in node.body:
                if not isinstance(statement.value, ast.Call):
                    raise ValueError(
                        "Only calls to 'CalmTask' methods supported inside parallel context."
                    )
                task = self.visit_Call(statement.value, return_task=True)
                if task:
                    parallel_tasks.append(task)
                    self.all_tasks.append(task)
            self.task_list.append(parallel_tasks)
        else:
            raise ValueError(
                "Unsupported context used in 'with' statement inside the action."
            ) 

def _find_sub_setup_call(
        self, elements
    ):  # type: (List[Any]) -> Tuple[Optional[ast.Call], Optional[List[Any]]]
        for element in elements:
            if not isinstance(element, (ast.FunctionDef, ast.If)):
                continue

            setup_call = self._find_setup_call(element.body)
            if setup_call != (None, None):
                setup_call, body = setup_call

                body = elements + body

                return setup_call, body

        return None, None 

def ensure_ctx_var(self, coro):

        d_list = []
        for d in coro.decorator_list:
            if isinstance(d, ast.Attribute):
                d_list.append(d.attr)
            elif isinstance(d, ast.Call):
                if isinstance(d.func, ast.Attribute):
                    d_list.append(d.func.attr)
        if 'command' not in d_list:
            return coro

        coro_args = [arg.arg for arg in coro.args.args]

        if not coro_args:
            coro.args.args.append(ast.arg(arg='ctx', annotation=None))
        elif 'self' in coro_args and 'ctx' not in coro_args:
            coro.args.args.insert(1, ast.arg(arg='ctx', annotation=None))
        elif 'self' not in coro_args and 'ctx' not in coro_args:
            coro.args.args.insert(0, ast.arg(arg='ctx', annotation=None))

        stats_counter['coro_changes'] += 1

        return coro 

def _extract_single_type_expr_arg(ast_node: ast.Call,
                                  called_fun_name: str,
                                  compilation_context: CompilationContext,
                                  in_match_pattern: bool,
                                  check_var_reference: Callable[[ast.Name], None],
                                  match_lambda_argument_names: Set[str],
                                  current_stmt_line: int):
    if ast_node.keywords:
        raise CompilationError(compilation_context, ast_node.keywords[0].value,
                               'Keyword arguments are not supported in %s()' % called_fun_name)

    if len(ast_node.args) != 1:
        raise CompilationError(compilation_context, ast_node, '%s() takes 1 argument. Got: %s' % (called_fun_name, len(ast_node.args)))
    [arg] = ast_node.args

    arg_ir = expression_ast_to_ir2(arg,
                                   compilation_context,
                                   in_match_pattern,
                                   check_var_reference,
                                   match_lambda_argument_names,
                                   current_stmt_line)
    if arg_ir.expr_type != ir2.TypeType():
        raise CompilationError(compilation_context, arg, 'The argument passed to %s() should have type Type, but was: %s' % (called_fun_name, str(arg_ir.expr_type)))
    return arg_ir 

def visit_BinOp(self, node):
        'Replace bitwise operation with function call'
        self.generic_visit(node)
        if isinstance(node.op, ast.BitAnd):
            return ast.Call(ast.Name('mand', ast.Load()),
                            [node.left, node.right], [], None, None)
        if isinstance(node.op, ast.BitOr):
            return ast.Call(ast.Name('mor', ast.Load()),
                            [node.left, node.right], [], None, None)
        if isinstance(node.op, ast.BitXor):
            return ast.Call(ast.Name('mxor', ast.Load()),
                            [node.left, node.right], [], None, None)
        if isinstance(node.op, ast.LShift):
            return ast.Call(ast.Name('mlshift', ast.Load()),
                            [node.left, node.right], [], None, None)
        if isinstance(node.op, ast.RShift):
            return ast.Call(ast.Name('mrshift', ast.Load()),
                            [node.left, node.right], [], None, None)
        return node 

def _apply_imports_to_unparsed_expression(exp_ast, imports):
  """Attempts to evaluate the code equivalent of `exp_ast`, with `imports`
  as available symbols. If it's successful, it returns the evaluated object.
  Otherwise this returns the unparsed code for `exp_ast`.

  Args:
    * exp_ast (Union[ast.Name, ast.Attribute, ast.Call]) - The expression to
      evaluate.
    * imports (Dict[str, object]) - The symbols to include during the evaluation
      of `exp_ast`.

  Returns the evaluation of `exp_ast` if it can successfully evaluate with
  `imports`. Otherwise this returns the source-code representation of exp_ast as
  a string.
  """
  assert isinstance(exp_ast, (ast.Name, ast.Attribute, ast.Call)), type(exp_ast)
  unparsed = _unparse(exp_ast).strip()
  try:
    return eval(unparsed, {'__builtins__': None}, imports)
  except (NameError, AttributeError):
    return unparsed 

def atomic_type_literal_ast_to_ir2(ast_node: ast.Call,
                                   compilation_context: CompilationContext,
                                   in_match_pattern: bool,
                                   check_var_reference: Callable[[ast.Name], None],
                                   match_lambda_argument_names: Set[str]):
    if ast_node.keywords:
        raise CompilationError(compilation_context, ast_node.keywords[0].value,
                               'Keyword arguments are not supported in Type()')

    if len(ast_node.args) != 1:
        raise CompilationError(compilation_context, ast_node, 'Type() takes 1 argument. Got: %s' % len(ast_node.args))
    [arg] = ast_node.args
    if not isinstance(arg, ast.Str):
        raise CompilationError(compilation_context, arg, 'The argument passed to Type should be a string constant.')
    _check_atomic_type(arg, compilation_context)
    return ir2.AtomicTypeLiteral(cpp_type=arg.s) 

def test_dump(self):
        node = ast.parse('spam(eggs, "and cheese")')
        self.assertEqual(ast.dump(node),
            "Module(body=[Expr(value=Call(func=Name(id='spam', ctx=Load()), "
            "args=[Name(id='eggs', ctx=Load()), Str(s='and cheese')], "
            "keywords=[], starargs=None, kwargs=None))])"
        )
        self.assertEqual(ast.dump(node, annotate_fields=False),
            "Module([Expr(Call(Name('spam', Load()), [Name('eggs', Load()), "
            "Str('and cheese')], [], None, None))])"
        )
        self.assertEqual(ast.dump(node, include_attributes=True),
            "Module(body=[Expr(value=Call(func=Name(id='spam', ctx=Load(), "
            "lineno=1, col_offset=0), args=[Name(id='eggs', ctx=Load(), "
            "lineno=1, col_offset=5), Str(s='and cheese', lineno=1, "
            "col_offset=11)], keywords=[], starargs=None, kwargs=None, "
            "lineno=1, col_offset=0), lineno=1, col_offset=0)])"
        ) 

def NAME(self, node):
        """
        Handle occurrence of Name (which can be a load/store/delete access.)
        """
        # Locate the name in locals / function / globals scopes.
        if isinstance(node.ctx, (ast.Load, ast.AugLoad)):
            self.handleNodeLoad(node)
            if (node.id == 'locals' and isinstance(self.scope, FunctionScope)
                    and isinstance(node.parent, ast.Call)):
                # we are doing locals() call in current scope
                self.scope.usesLocals = True
        elif isinstance(node.ctx, (ast.Store, ast.AugStore)):
            self.handleNodeStore(node)
        elif isinstance(node.ctx, ast.Del):
            self.handleNodeDelete(node)
        else:
            # must be a Param context -- this only happens for names in function
            # arguments, but these aren't dispatched through here
            raise RuntimeError("Got impossible expression context: %r" % (node.ctx,)) 

def visit_For(self, node):
        node.breakLabel = _Label("BREAK")
        node.loopLabel = _Label("LOOP")
        self.labelStack.append(node.breakLabel)
        self.labelStack.append(node.loopLabel)
        self.refStack.push()
        self.visit(node.target)
        var = node.target.id
        self.tree.vardict[var] = int(-1)

        cf = node.iter
        self.visit(cf)
        self.require(node, isinstance(cf, ast.Call), "Expected (down)range call")
        f = self.getObj(cf.func)
        self.require(node, f in (range, downrange), "Expected (down)range call")

        for stmt in node.body:
            self.visit(stmt)
        self.refStack.pop()
        self.require(node, not node.orelse, "for-else not supported")
        self.labelStack.pop()
        self.labelStack.pop() 

def _find_sub_setup_call(
        self, elements
    ):  # type: (List[Any]) -> Tuple[Optional[ast.Call], Optional[List[Any]]]
        for element in elements:
            if not isinstance(element, (ast.FunctionDef, ast.If)):
                continue

            setup_call = self._find_setup_call(element.body)
            if setup_call != (None, None):
                setup_call, body = setup_call

                body = elements + body

                return setup_call, body

        return None, None 

def visit_Call(self, call):
        """
        visit `ast.Call` nodes
        """
        new_func, func_expl = self.visit(call.func)
        arg_expls = []
        new_args = []
        new_kwargs = []
        for arg in call.args:
            res, expl = self.visit(arg)
            arg_expls.append(expl)
            new_args.append(res)
        for keyword in call.keywords:
            res, expl = self.visit(keyword.value)
            new_kwargs.append(ast.keyword(keyword.arg, res))
            if keyword.arg:
                arg_expls.append(keyword.arg + "=" + expl)
            else:  # **args have `arg` keywords with an .arg of None
                arg_expls.append("**" + expl)

        expl = "{}({})".format(func_expl, ", ".join(arg_expls))
        new_call = ast.Call(new_func, new_args, new_kwargs)
        res = self.assign(new_call)
        res_expl = self.explanation_param(self.display(res))
        outer_expl = "{}\n{{{} = {}\n}}".format(res_expl, res_expl, expl)
        return res, outer_expl 

def _find_call_kwargs(self, call):  # type: (ast.Call) -> Optional[Any]
        kwargs = None
        for keyword in call.keywords:
            if keyword.arg is None:
                kwargs = keyword.value

        return kwargs 

def bool_iterable_all_expr_ast_to_ir2(ast_node: ast.Call,
                                      compilation_context: CompilationContext,
                                      in_match_pattern: bool,
                                      check_var_reference: Callable[[ast.Name], None],
                                      current_stmt_line: int):
    if in_match_pattern:
        raise CompilationError(compilation_context, ast_node,
                               'all() is not allowed in match patterns')

    if ast_node.keywords:
        raise CompilationError(compilation_context, ast_node.keywords[0].value, 'Keyword arguments are not supported.')
    if len(ast_node.args) != 1:
        raise CompilationError(compilation_context, ast_node, 'all() takes 1 argument. Got: %s' % len(ast_node.args))
    [arg] = ast_node.args
    arg_expr = expression_ast_to_ir2(arg,
                                     compilation_context,
                                     in_match_pattern,
                                     check_var_reference,
                                     match_lambda_argument_names=set(),
                                     current_stmt_line=current_stmt_line)
    if not (isinstance(arg_expr.expr_type, (ir2.ListType, ir2.SetType)) and isinstance(arg_expr.expr_type.elem_type, ir2.BoolType)):
        notes = []
        if isinstance(arg_expr, ir2.VarReference):
            lookup_result = compilation_context.get_symbol_definition(arg_expr.name)
            assert lookup_result
            assert not lookup_result.is_only_partially_defined
            notes.append((lookup_result.ast_node, '%s was defined here' % arg_expr.name))
        raise CompilationError(compilation_context, arg,
                               'The argument of all() must have type List[bool] or Set[bool]. Got type: %s' % str(arg_expr.expr_type),
                               notes=notes)
    if isinstance(arg_expr.expr_type, ir2.ListType):
        return ir2.BoolListAllExpr(list_expr=arg_expr)
    else:
        return ir2.BoolSetAllExpr(set_expr=arg_expr) 

def bool_iterable_any_expr_ast_to_ir2(ast_node: ast.Call,
                                      compilation_context: CompilationContext,
                                      in_match_pattern: bool,
                                      check_var_reference: Callable[[ast.Name], None],
                                      current_stmt_line: int):
    if in_match_pattern:
        raise CompilationError(compilation_context, ast_node,
                               'any() is not allowed in match patterns')

    if ast_node.keywords:
        raise CompilationError(compilation_context, ast_node.keywords[0].value, 'Keyword arguments are not supported.')
    if len(ast_node.args) != 1:
        raise CompilationError(compilation_context, ast_node, 'any() takes 1 argument. Got: %s' % len(ast_node.args))
    [arg] = ast_node.args
    arg_expr = expression_ast_to_ir2(arg,
                                     compilation_context,
                                     in_match_pattern,
                                     check_var_reference,
                                     match_lambda_argument_names=set(),
                                     current_stmt_line=current_stmt_line)
    if not (isinstance(arg_expr.expr_type, (ir2.ListType, ir2.SetType)) and isinstance(arg_expr.expr_type.elem_type, ir2.BoolType)):
        notes = []
        if isinstance(arg_expr, ir2.VarReference):
            lookup_result = compilation_context.get_symbol_definition(arg_expr.name)
            assert lookup_result
            assert not lookup_result.is_only_partially_defined
            notes.append((lookup_result.ast_node, '%s was defined here' % arg_expr.name))
        raise CompilationError(compilation_context, arg,
                               'The argument of any() must have type List[bool] or Set[bool]. Got type: %s' % str(arg_expr.expr_type),
                               notes=notes)
    if isinstance(arg_expr.expr_type, ir2.ListType):
        return ir2.BoolListAnyExpr(list_expr=arg_expr)
    else:
        return ir2.BoolSetAnyExpr(set_expr=arg_expr) 

def test_fix_missing_locations(self):
        src = ast.parse('write("spam")')
        src.body.append(ast.Expr(ast.Call(ast.Name('spam', ast.Load()),
                                          [ast.Str('eggs')], [], None, None)))
        self.assertEqual(src, ast.fix_missing_locations(src))
        self.assertEqual(ast.dump(src, include_attributes=True),
            "Module(body=[Expr(value=Call(func=Name(id='write', ctx=Load(), "
            "lineno=1, col_offset=0), args=[Str(s='spam', lineno=1, "
            "col_offset=6)], keywords=[], starargs=None, kwargs=None, "
            "lineno=1, col_offset=0), lineno=1, col_offset=0), "
            "Expr(value=Call(func=Name(id='spam', ctx=Load(), lineno=1, "
            "col_offset=0), args=[Str(s='eggs', lineno=1, col_offset=0)], "
            "keywords=[], starargs=None, kwargs=None, lineno=1, "
            "col_offset=0), lineno=1, col_offset=0)])"
        ) 

def _find_single_string(
        self, call, body, name
    ):  # type: (ast.Call, List[Any], str) -> Optional[str]
        value = self._find_in_call(call, name)
        if value is None:
            # Trying to find in kwargs
            kwargs = self._find_call_kwargs(call)

            if kwargs is None or not isinstance(kwargs, ast.Name):
                return

            variable = self._find_variable_in_body(body, kwargs.id)
            if not isinstance(variable, (ast.Dict, ast.Call)):
                return

            if isinstance(variable, ast.Call):
                if not isinstance(variable.func, ast.Name):
                    return

                if variable.func.id != "dict":
                    return

                value = self._find_in_call(variable, name)
            else:
                value = self._find_in_dict(variable, name)

        if value is None:
            return

        if isinstance(value, ast.Str):
            return value.s
        elif isinstance(value, ast.Name):
            variable = self._find_variable_in_body(body, value.id)

            if variable is not None and isinstance(variable, ast.Str):
                return variable.s 

def _find_install_requires(
        self, call, body
    ):  # type: (ast.Call, Iterable[Any]) -> List[str]
        install_requires = []
        value = self._find_in_call(call, "install_requires")
        if value is None:
            # Trying to find in kwargs
            kwargs = self._find_call_kwargs(call)

            if kwargs is None or not isinstance(kwargs, ast.Name):
                return install_requires

            variable = self._find_variable_in_body(body, kwargs.id)
            if not isinstance(variable, (ast.Dict, ast.Call)):
                return install_requires

            if isinstance(variable, ast.Call):
                if not isinstance(variable.func, ast.Name):
                    return install_requires

                if variable.func.id != "dict":
                    return install_requires

                value = self._find_in_call(variable, "install_requires")
            else:
                value = self._find_in_dict(variable, "install_requires")

        if value is None:
            return install_requires

        if isinstance(value, ast.List):
            for el in value.elts:
                install_requires.append(el.s)
        elif isinstance(value, ast.Name):
            variable = self._find_variable_in_body(body, value.id)

            if variable is not None and isinstance(variable, ast.List):
                for el in variable.elts:
                    install_requires.append(el.s)

        return install_requires 

def type_reference_expr_ast_to_ir2(ast_node: ast.Call,
                                   compilation_context: CompilationContext,
                                   in_match_pattern: bool,
                                   check_var_reference: Callable[[ast.Name], None],
                                   match_lambda_argument_names: Set[str],
                                   current_stmt_line: int):
    return ir2.ReferenceTypeExpr(_extract_single_type_expr_arg(ast_node,
                                                               'Type.reference',
                                                               compilation_context,
                                                               in_match_pattern,
                                                               check_var_reference,
                                                               match_lambda_argument_names,
                                                               current_stmt_line)) 

def visit_BoolOp(self, boolop):
        res_var = self.variable()
        expl_list = self.assign(ast.List([], ast.Load()))
        app = ast.Attribute(expl_list, "append", ast.Load())
        is_or = int(isinstance(boolop.op, ast.Or))
        body = save = self.statements
        fail_save = self.expl_stmts
        levels = len(boolop.values) - 1
        self.push_format_context()
        # Process each operand, short-circuiting if needed.
        for i, v in enumerate(boolop.values):
            if i:
                fail_inner = []
                # cond is set in a prior loop iteration below
                self.expl_stmts.append(ast.If(cond, fail_inner, []))  # noqa
                self.expl_stmts = fail_inner
            self.push_format_context()
            res, expl = self.visit(v)
            body.append(ast.Assign([ast.Name(res_var, ast.Store())], res))
            expl_format = self.pop_format_context(ast.Str(expl))
            call = ast.Call(app, [expl_format], [])
            self.expl_stmts.append(ast.Expr(call))
            if i < levels:
                cond = res
                if is_or:
                    cond = ast.UnaryOp(ast.Not(), cond)
                inner = []
                self.statements.append(ast.If(cond, inner, []))
                self.statements = body = inner
        self.statements = save
        self.expl_stmts = fail_save
        expl_template = self.helper("_format_boolop", expl_list, ast.Num(is_or))
        expl = self.pop_format_context(expl_template)
        return ast.Name(res_var, ast.Load()), self.explanation_param(expl) 

def visit_Name(self, name):
        # Display the repr of the name if it's a local variable or
        # _should_repr_global_name() thinks it's acceptable.
        locs = ast.Call(self.builtin("locals"), [], [])
        inlocs = ast.Compare(ast.Str(name.id), [ast.In()], [locs])
        dorepr = self.helper("_should_repr_global_name", name)
        test = ast.BoolOp(ast.Or(), [inlocs, dorepr])
        expr = ast.IfExp(test, self.display(name), ast.Str(name.id))
        return name, self.explanation_param(expr) 

def helper(self, name, *args):
        """Call a helper in this module."""
        py_name = ast.Name("@pytest_ar", ast.Load())
        attr = ast.Attribute(py_name, name, ast.Load())
        return ast.Call(attr, list(args), []) 

def visit_Call(self, call):
        """
        visit `ast.Call` nodes
        """
        new_func, func_expl = self.visit(call.func)
        arg_expls = []
        new_args = []
        new_kwargs = []
        for arg in call.args:
            res, expl = self.visit(arg)
            arg_expls.append(expl)
            new_args.append(res)
        for keyword in call.keywords:
            res, expl = self.visit(keyword.value)
            new_kwargs.append(ast.keyword(keyword.arg, res))
            if keyword.arg:
                arg_expls.append(keyword.arg + "=" + expl)
            else:  # **args have `arg` keywords with an .arg of None
                arg_expls.append("**" + expl)

        expl = "{}({})".format(func_expl, ", ".join(arg_expls))
        new_call = ast.Call(new_func, new_args, new_kwargs)
        res = self.assign(new_call)
        res_expl = self.explanation_param(self.display(res))
        outer_expl = "{}\n{{{} = {}\n}}".format(res_expl, res_expl, expl)
        return res, outer_expl 

def visit_BoolOp(self, boolop):
        res_var = self.variable()
        expl_list = self.assign(ast.List([], ast.Load()))
        app = ast.Attribute(expl_list, "append", ast.Load())
        is_or = int(isinstance(boolop.op, ast.Or))
        body = save = self.statements
        fail_save = self.expl_stmts
        levels = len(boolop.values) - 1
        self.push_format_context()
        # Process each operand, short-circuiting if needed.
        for i, v in enumerate(boolop.values):
            if i:
                fail_inner = []
                # cond is set in a prior loop iteration below
                self.expl_stmts.append(ast.If(cond, fail_inner, []))  # noqa
                self.expl_stmts = fail_inner
            self.push_format_context()
            res, expl = self.visit(v)
            body.append(ast.Assign([ast.Name(res_var, ast.Store())], res))
            expl_format = self.pop_format_context(ast.Str(expl))
            call = ast.Call(app, [expl_format], [])
            self.expl_stmts.append(ast.Expr(call))
            if i < levels:
                cond = res
                if is_or:
                    cond = ast.UnaryOp(ast.Not(), cond)
                inner = []
                self.statements.append(ast.If(cond, inner, []))
                self.statements = body = inner
        self.statements = save
        self.expl_stmts = fail_save
        expl_template = self.helper("_format_boolop", expl_list, ast.Num(is_or))
        expl = self.pop_format_context(expl_template)
        return ast.Name(res_var, ast.Load()), self.explanation_param(expl) 

def visit_Name(self, name):
        # Display the repr of the name if it's a local variable or
        # _should_repr_global_name() thinks it's acceptable.
        locs = ast.Call(self.builtin("locals"), [], [])
        inlocs = ast.Compare(ast.Str(name.id), [ast.In()], [locs])
        dorepr = self.helper("_should_repr_global_name", name)
        test = ast.BoolOp(ast.Or(), [inlocs, dorepr])
        expr = ast.IfExp(test, self.display(name), ast.Str(name.id))
        return name, self.explanation_param(expr) 

def helper(self, name, *args):
        """Call a helper in this module."""
        py_name = ast.Name("@pytest_ar", ast.Load())
        attr = ast.Attribute(py_name, name, ast.Load())
        return ast.Call(attr, list(args), [])