code: def update(environment, zappa_settings):
      
      print(("Updating " + environment))
  
      # Package dependencies, and the source code into a zip
      zappa, settings, lambda_name, zip_path = \
          _package(environment, zappa_settings)
  
      s3_bucket_name = settings['s3_bucket']
  
      try:
  
          # Load your AWS credentials from ~/.aws/credentials
          zappa.load_credentials()
  
          # Update IAM roles if needed
          zappa.create_iam_roles()
  
  
          # Upload it to S3
          zip_arn = zappa.upload_to_s3(zip_path, s3_bucket_name)
  
          # Register the Lambda function with that zip as the source
          # You'll also need to define the path to your lambda_handler code.
          lambda_arn = zappa.update_lambda_function(s3_bucket_name, zip_path,
                                                    lambda_name)
  
          # Remove the uploaded zip from S3, because it is now registered..
          zappa.remove_from_s3(zip_path, s3_bucket_name)
      finally:
          try:
              # Finally, delete the local copy our zip package
              if settings['delete_zip']:
                  os.remove(zip_path)
          except:
              print("WARNING: Manual cleanup of the zip might be needed.")
  
      print("Your updated Zappa deployment is live!")
docs: Update an existing deployment.