(self, rules)
Select candidate rules to be further specialised.

        Parameters
        ----------
        rules : list of Rule
            An ordered list of rules (best come first).

        Returns
        -------
        candidate_rules : list of Rule
            Chosen rules.
        rules : list of Rule
            Rules not chosen, i.e. the remainder.
Select candidate rules to be further specialised.
Select candidate rules to be further specialised .
def select_candidates(self, rules):
        """
        Select candidate rules to be further specialised.

        Parameters
        ----------
        rules : list of Rule
            An ordered list of rules (best come first).

        Returns
        -------
        candidate_rules : list of Rule
            Chosen rules.
        rules : list of Rule
            Rules not chosen, i.e. the remainder.
        """
        raise NotImplementedError
def select_candidates ( self , rules ) : raise NotImplementedError