'Retrieve message information.
Arguments:
access_point (str): Either \'enrollment\' or \'courseware\'
message_key (str): The identifier for which message to show.
Returns:
embargo.messages.BlockedMessage or None'

def _message(self, access_point, message_key):

    message_dict = dict()
    if (access_point == self.ENROLLMENT_ACCESS_POINT):
        message_dict = messages.ENROLL_MESSAGES
    elif (access_point == self.COURSEWARE_ACCESS_POINT):
        message_dict = messages.COURSEWARE_MESSAGES
    return message_dict.get(message_key)
