def _get_flow_for_token(csrf_token):
flow_pickle = session.pop(<EOL>_FLOW_KEY.format(csrf_token), None)<EOL>if flow_pickle is None:<EOL><INDENT>return None<EOL><DEDENT>else:<EOL><INDENT>return pickle.loads(flow_pickle)<EOL><DEDENT>
Retrieves the flow instance associated with a given CSRF token from
    the Flask session.