From 4c61aaf1dc09aa46fe0e4248e326bd7cf78fd2b7 Mon Sep 17 00:00:00 2001
From: Erez Sh <erezshin@gmail.com>
Date: Mon, 4 May 2020 13:30:47 +0300
Subject: [PATCH] Small refactoring for iter_subtrees

---
 lark/tree.py | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/lark/tree.py b/lark/tree.py
index e2e41d9..84c996a 100644
--- a/lark/tree.py
+++ b/lark/tree.py
@@ -62,14 +62,12 @@ class Tree(object):
         queue = [self]
         subtrees = OrderedDict()
         for subtree in queue:
-            if id(subtree) in subtrees:
-                continue
             subtrees[id(subtree)] = subtree
-            queue += [c for c in reversed(subtree.children) if isinstance(c, Tree)]
+            queue += [c for c in reversed(subtree.children)
+                      if isinstance(c, Tree) and id(c) not in subtrees]
 
         del queue
-        for subtree in reversed(list(subtrees.values())):
-            yield subtree
+        return reversed(list(subtrees.values()))
 
     def find_pred(self, pred):
         "Find all nodes where pred(tree) == True"