For each special method, you should show what syntax magically invokes it. Something like this:
foo.__iter__() is invoked by for x in foo
a.__iadd__(b) is invoked by a += b
a.__rmult__(b) is invoked by b * a when b * a fails.
foo.__len__() is invoked by if foo when foo.__bool__ or foo.__nonzero__ is not defined.
foo.__repr__() is invoked by '%r' % foo, also by pprint.pprint(foo) and deprecated `foo`. It's also invoked by __str__ magic when foo.__str__ is not defined.
etc.
Putting the above info in a table would also be helpful.
I think the answer for this is different for fiction and non-fiction. If I don't finish a non-fiction book, I still sometimes consider it "read", if I have gotten the gest of it. This is especially true if the author goes into more detail towards the end of the book after making their point. Non-completed fiction books I usually don't recommend to friends.
My first thought, as suggested by some on the list, was modularization. Redstone's response (that the 1.3 million files are essentially all interdependent) terrifies me.
foo.__iter__() is invoked by for x in foo a.__iadd__(b) is invoked by a += b a.__rmult__(b) is invoked by b * a when b * a fails. foo.__len__() is invoked by if foo when foo.__bool__ or foo.__nonzero__ is not defined. foo.__repr__() is invoked by '%r' % foo, also by pprint.pprint(foo) and deprecated `foo`. It's also invoked by __str__ magic when foo.__str__ is not defined. etc. Putting the above info in a table would also be helpful.