diff -r cabe3b5d5139 -r 09337aae08d4 hgext3rd/topic/revset.py
--- a/hgext3rd/topic/revset.py	Wed Dec 05 23:13:26 2018 +0800
+++ b/hgext3rd/topic/revset.py	Wed Dec 05 23:15:29 2018 +0800
@@ -82,9 +82,9 @@
 
     Name is horrible so that people change it.
     """
-    args = revset.getargs(x, 1, 1, 'topic takes one')
+    args = revset.getargs(x, 1, 1, 'ngtip takes one argument')
     # match a specific topic
-    branch = revset.getstring(args[0], 'ngtip() argument must be a string')
+    branch = revset.getstring(args[0], 'ngtip requires a string')
     if branch == '.':
         branch = repo['.'].branch()
     return subset & revset.baseset(destination.ngtip(repo, branch))
@@ -95,8 +95,9 @@
 
     This is roughly equivalent to 'topic(.) - obsolete' with a sorting moving
     unstable changeset after there future parent (as if evolve where already
-    run)."""
-    err = 'stack() takes no argument, it works on current topic'
+    run).
+    """
+    err = 'stack takes no arguments, it works on current topic'
     revset.getargs(x, 0, 0, err)
     topic = None
     branch = None