def __repr__(self):
        return "<Requirement(package={package}, version='{version}')>".format(
            package=self.package, version=self.version)
def tag(self, g):
        self.g = g
        self.g.beginPath()
        self.g.fillText("%d, %d"%(self.x, self.y),self.x, self.y)
        self.g.stroke()