class P(object):
    def __init__(self, x):
        self._x = x

    @property
    def x(self):
        return self._x

    @x.setter
    def x(self, x):
        if x < 0:
            self._x = 0
        elif x > 1000:
            self._x = 1000
        else:
            self._x = x