def get_leaves(node):
	"""
	Get the leaf nodes in the passed expression
	tree (the logical expression operands)
	"""
	if not node:
		return []

	leaves = []
	stack = [node]
	while stack:
		n = stack.pop()
		if not n:
			continue
		if not (n.left or n.right):
			leaves.append(n)
		else:
			stack.append(n.left)
			stack.append(n.right)
	return leaves