diff --git a/jedi/parser/tree.py b/jedi/parser/tree.py
index 05de527b..1b6a2666 100644
--- a/jedi/parser/tree.py
+++ b/jedi/parser/tree.py
@@ -3,6 +3,14 @@ from jedi._compatibility import utf8_repr, encoding, is_py3
 
 
 def search_ancestor(node, node_type_or_types):
+    """
+    Recursively looks at the parents of a node and checks if the type names
+    match.
+
+    :param node: The node that is looked at.
+    :param node_type_or_types: A tuple or a string of type names that are
+        searched for.
+    """
     if not isinstance(node_type_or_types, (list, tuple)):
         node_type_or_types = (node_type_or_types,)