def __repr__(self):
        return "<Requirement(package={package}, version='{version}')>".format(
            package=self.package, version=self.version)
def paint(self, c):
		self.leaf.paint(c)
		if self.lchild != None:
			self.lchild.paint(c)
		if self.rchild != None:
			self.rchild.paint(c)