def _check_lambda(self):
        """Check if lambda function exists.

        Returns:
            True if function does exist
            False if function does not exist
        """
        exists = False
        try:
            self.lambda_client.get_function(FunctionName=self.app_name)
            exists = True
        except boto3.exceptions.botocore.exceptions.ClientError:
            pass
        return exists
Check if lambda function exists.

        Returns:
            True if function does exist
            False if function does not exist