def grow(self, depth=1e900000):
	'''Grow the tree of GameStates, starting from this one.

	Assumptions:
	The tree of GameStates generated from this one is finite, and is
	specified (recursively) by self.value.make_move()
	'''

	if depth == 0:
		return self

	h = hash(self.value)

	if h not in gamestates:

		for m in self.value.next_move():
			child = GameStateNode(self.value.make_move(m), m)
			child = child.grow(depth -1)
			self.children.append(child)

		gamestates[h] = self

	else:
		for child in gamestates[h].children:
			self.children.append(child)

	return gamestates[h]