Eclipse offers an comfortable IDE environment for developing and debugging.
Install Eclipse.
Install the pydev plugin (now published under the EPL and is free... :) and the mercurial plugin.
- File menu -> Import
- Mercurial -> Clone existing Mercurial repository: http://hanji.info/hgweb.cgi
- Give a title to your project (hanji_project).
Start the debug configuration to set breakpoints, watch variables, as described in the Eclipse and PyDev documentation.