class Point(tuple):
    '''Represents an (x,y) coordinate'''
    def __new__(cls, x, y):
        return tuple.__new__(cls, (y, x))
    def __getattr__(self, name):
        if name == "x":
            return self[1]
        elif name == 'y':
            return self[0]
        else:
            raise AttributeError
    def __repr__(self):
        return '<Point(%d, %d)>' % (self[1], self[0])
    def __str__(self):
        return '(%d,%d)' % (self[1], self[0])

    def xy(self):
        '''Returns a tuple (x,y)'''
        return (self[1], self[0])
    def yx(self):
        '''Returns a tuple (x,y)'''
        return tuple(self)
    def add(self, xdelta, ydelta):
        '''Returns a new point, adding xdelta and ydelta'''
        return Point(self[1] + xdelta, self[0] + ydelta)
    def vadd(self, xdelta, ydelta):
        '''Returns a new point. If ydelta != 0, xdelta is absolute; otherwise, xdelta is relative'''
        assert xdelta >= 0 and ydelta >= 0, str((xdelta, ydelta))
        if ydelta != 0:
            return Point(xdelta, self[0] + ydelta)
        else:
            return Point(self[1] + xdelta, self[0])
    #def sub(self, xdelta, ydelta):
    #    '''Returns a new point, subtracing xdelta and ydelta'''
    #    return Point(self[1] - xdelta, self[0] - ydelta)
    #def vsub(self, xdelta, ydelta):
    #    '''Returns a new point. If ydelta != 0, xdelta is absolute; otherwise, xdelta is relative'''
    #    assert xdelta >= 0 and ydelta >= 0, str((xdelta, ydelta))
    #    if ydelta != 0:
    #        return Point(self[1], self[0] - ydelta)
    #    else:
    #        return Point(self[1] - xdelta, self[0])