def searchMemberData(search_param, search_term, attributes=()):
    """ Return a sequence of mappings of memberdata for the given criteria.

        o 'search_param' is the property ID to be searched.

        o 'search_term' is the property value to be searched.

        o 'attributes', if passed, controls the keys in the returned mappings;
          by default the returned keys are 'username' and 'email'.

        o ???:  that default is silly;  if it is truly needed, then it should
          be the default value of the 'attributes' argument.

        o Permission:  Private (Python only)
        """
