Debugging

--> Turn ENABLED to True in debug.py will let mathmaker write debugging informations to stderr. The methods that give output informations can be chosen among the different variable below (into_str_in_item, into_str_in_product etc.). All objects have a special (small) method called dbg_str() which is used to clearly identify the objects and their classes. (I can see in your snip : {+1^.1.} and {-0^.1.}, which represent Item(1) and Item(0), so there was some debugging stuff enabled there)
--> The autotest-mathmaker executable in the main directory uses the tests present in maintenance/autotest