@classmethod
def _find_localzeros(cls, values, **options):
    """
        Sequentially allocate values to localzeros.

        When a value is identified as being more extreme than another member it
        replaces that member; if this is never true, then the value is simply
        appended to the localzeros.

        """
    localzeros = set()
    for v in values:
        is_newzero = True
        localzeros_ = list(localzeros)
        for z in localzeros_:
            assert v != z
            con = cls._is_connected(v, z)
            if con:
                is_newzero = False
                if con is True or con == cls:
                    localzeros.remove(z)
                    localzeros.update([v])
        if is_newzero:
            localzeros.update([v])
    return localzeros
