def METHOD_NAME(self, sig):
    if sig is None:
        return None
    assert len(sig) == 1
    idx = 0
    while isinstance(sig, _Slice) and hasattr(sig, "value"):
        idx = sig.start
        sig = sig.value
    sc = self.constraint_manager.get_sig_constraints()
    for s, pins, others, resource in sc:
        if (s == sig) and (pins[0] != 'X'):
                return [pins[idx]]
    return None