def serialized(self):
        to_ret = {}
        for group, requirements in self.items():
            to_ret[group] = [str(requirement) for requirement in requirements]
        return to_ret
def get_level(self, level, queue):
		if queue == None:
			queue = []
		if level == 1:
			queue.push(self)
		else:
			if self.lchild != None:
				self.lchild.get_level(level-1, queue)
			if self.rchild != None:
				self.rchild.get_level(level-1, queue)
		return queue