Split before first elem in list

If the list terminates with a comma, then we want to split before all elements
including the first element, assuming that there's more than one element in the
lsit.

Closes #313
diff --git a/yapftests/pytree_unwrapper_test.py b/yapftests/pytree_unwrapper_test.py
index 057e037..7d98067 100644
--- a/yapftests/pytree_unwrapper_test.py
+++ b/yapftests/pytree_unwrapper_test.py
@@ -57,8 +57,10 @@
     """
     actual = []
     for uwl in uwlines:
-      filtered_values = [ft.value for ft in uwl.tokens
-                         if ft.name not in pytree_utils.NONSEMANTIC_TOKENS]
+      filtered_values = [
+          ft.value for ft in uwl.tokens
+          if ft.name not in pytree_utils.NONSEMANTIC_TOKENS
+      ]
       actual.append((uwl.depth, filtered_values))
 
     self.assertEqual(list_of_expected, actual)