Todd,

Tabify/Untabify are functions to deal with the great tabs vs. spaces debate (though PEP8 says that spaces are the way to go). 

The tabify function needs a minimum of 2 spaces before it replaces it with a tab.

Its implementation in Lib/idlelib/EditorWindow.py under the tabify_region_event and untabify_region_event reveals a curiousity in its implementation. Tabify will replace spans of space characters with tabs, but still leave in extra space characters if needed. Untabify simply expands all tabs to a fixed number of spaces.