1 files changed, 12 insertions, 3 deletions
diff --git a/python/google/protobuf/message.py b/python/google/protobuf/message.py
index c186452a..88ed9f4c 100755
--- a/python/google/protobuf/message.py
+++ b/python/google/protobuf/message.py
@@ -233,12 +233,21 @@ class Message(object):
     raise NotImplementedError
 
   def HasField(self, field_name):
-    """Checks if a certain field is set for the message. Note if the
-    field_name is not defined in the message descriptor, ValueError will be
-    raised."""
+    """Checks if a certain field is set for the message, or if any field inside
+    a oneof group is set.  Note that if the field_name is not defined in the
+    message descriptor, ValueError will be raised."""
     raise NotImplementedError
 
   def ClearField(self, field_name):
+    """Clears the contents of a given field, or the field set inside a oneof
+    group.  If the name neither refers to a defined field or oneof group,
+    ValueError is raised."""
+    raise NotImplementedError
+
+  def WhichOneof(self, oneof_group):
+    """Returns the name of the field that is set inside a oneof group, or
+    None if no field is set.  If no group with the given name exists, ValueError
+    will be raised."""
     raise NotImplementedError
 
   def HasExtension(self, extension_handle):