def is_class_session(session):
    """
    Check is a session has a class_session type.

    :param: session: The session to check.
    :type: session: {Str:Str}

    :return: True if the session is of class_session type, False otherwise.
    :rtype: bool
    """
    try:
        session_type = session['type']
        return session_type == 'class_session'
    except KeyError:
        return False