def __init__(self, name, filename=None):
        self.name = name
        super(NamedRequirements, self).__init__(filename=filename)
def _on_size_spin_button_value_changed(self, size_spin_button):
    if self._locker.is_unlocked("emit_size_spin_button_value_changed"):
      self._locker.lock("update_spin_button")