@classmethod
def import_it(cls):
    """
        Performs the import only once.
        """
    if not cls in cls._FEATURES:
        try:
            cls._FEATURES[cls] = cls._import_it()
        except ImportError:
            raise cls.Error(cls._import_error_message(), cls.Error.
                UNSATISFIED_IMPORT_REQ)
    return cls._FEATURES[cls]
