python abstract base classes, difference between mixin & abstract method -

the following table shows varying abstract base classes used on python. however, bit confused (in context)

what difference between abstract methods column , mixin methods column. 1 optionally implemented , other not?

i've been mulling on , every 1 of "theories" doesn't seem right.

reference

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anything in abstract methods column, have implement yourself. abc provides default implementations of methods in mixin methods column, implemented in terms of methods have write.