python source code of lambda

#!/usr/bin/env python

import boto3
import os
import random 
import string

'''
This lambda handler submits a job to a AWS Batch queue.
JobQueue, and JobDefinition environment variables must be set. 
These environment variables are intended to be set to the Name, not the Arn. 
'''
def lambda_handler(event,context):
    # Grab data from environment
    jobqueue = os.environ['JobQueue']
    jobdef = os.environ['JobDefinition']

    # Create unique name for the job (this does not need to be unique)
    job1Name = 'job1' + ''.join(random.choices(string.ascii_uppercase + string.digits, k=4))

    # Set up a batch client 
    session = boto3.session.Session()
    client = session.client('batch')

    # Submit the job
    job1 = client.submit_job(
        jobName=job1Name,
        jobQueue=jobqueue,
        jobDefinition=jobdef
    )
    print("Started Job: {}".format(job1['jobName']))