@classmethod
def normalise(cls, query_comparator):
    """Get a normalised form of the representation of a query.

        :return: None, a matcher or something suitable for AnyMapping.
        """
    if query_comparator is None:
        return None
    if isinstance(query_comparator, str):
        return cls._from_query_string(query_comparator)
    return query_comparator
