def METHOD_NAME(
        self, user_pool_id, client_id, auth_flow, user_name, password, challenge_name,
        challenge_parameters, session, client_secret_hash=None, error_code=None):
    expected_params = {
        'UserPoolId': user_pool_id, 'ClientId': client_id, 'AuthFlow': auth_flow,
        'AuthParameters': {'USERNAME': user_name, 'PASSWORD': password}}
    if client_secret_hash is not None:
        expected_params['AuthParameters']['SECRET_HASH'] = client_secret_hash
    response = {
        'ChallengeName': challenge_name, 'ChallengeParameters': challenge_parameters,
        'Session': session}
    self._stub_bifurcator(
        'admin_initiate_auth', expected_params, response, error_code=error_code)