def on(self, on: BinaryExpression) -> None:
    if (self.on_ is None):
        self.on_ = on
        return
    self.on_ = (self.on_ & on)
def on(self, on: BinaryExpression) -> None:
    if (self.on_ is None):
        self.on_ = on
        return
    self.on_ = (self.on_ & on)