@classmethod
def remove_prefix(cls, suffix):
    """"Remove the class prefix from the suffix

        The collection pass the full suffix used in the filters to the index.
        But to know if it is valid, we have to remove the prefix to get the
        real suffix, for example to check if the suffix is handled by the index.

        Parameters
        -----------
        suffix: str
            The full suffix to split

        Returns
        -------
        str or None
            The suffix without the prefix. None if the resting suffix is ''

        Raises
        ------
        IndexError:
            If the suffix doesn't contain the prefix

        """
    if not cls.prefix:
        return suffix
    if cls.prefix == suffix:
        return None
    return (suffix or '').split(cls.prefix + '__')[1] or None
