"assert undefined" - i thought it wa sin my source file.

C:\Users\dm\mongo>mongo --shell ..\mongo-snippets\replication\test_latency.js localhost:27000
MongoDB shell version: 1.5.2-pre-
url: test
connecting to: test
loading file: ..\mongo-snippets\replication\test_latency.js
assert: assert failed : undefined
Fri May 07 19:52:34 JS Error: uncaught exception: assert failed : undefined
failed to load: ..\mongo-snippets\replication\test_latency.js