Simply returns the versions available for a Lambda function, given a function name.

def get_lambda_function_versions(self, function_name):
        """
        Simply returns the versions available for a Lambda function, given a function name.

        """
        try:
            response = self.lambda_client.list_versions_by_function(
                FunctionName=function_name
            )
            return response.get('Versions', [])
        except Exception:
            return []