Thank you for writing this.  I was NOT looking forward to tackling tests for this module.

I have thought about merging delegator and colorizer into one module, possibly with percolator included, and adding a module docstring that explains how they work together.  This would still be only a few hundred lines.  (And multiple htests in one file are not an issue.)  What do you think?

There is a suggestion in percolater that Percolater could subclass Delegator.  I have not seriously looked at that idea yet.

In the first code comment I mentioned a follow-up code change.  Did you have anything in mind to work on or did you pick this for the fun and challenge?