Program.all_inherits has a FIXME asking for docs. But its definition is a little odd: it returns a list of the given program's inherits, and everything they inherit - but not recursively.
I could document it as such, but it strikes me that this should be recursive, similar to inherit_tree but returning a flat array. Example implementation in branch rosuav/pgm_all_inherits - what do you think?
ChrisA