The __add__ method
__add__(self, other)
These methods are called to implement the binary arithmetic operations
(+, -, \*, //, %, divmod(), pow(), \*\*, <``<, `
>`>, &, ^, |). For instance, to evaluate the
expression x+y, where x is an instance of a class that has an
__add__ method, x.\_\_add\_\_(y) is called. The
__divmod__ method should be the equivalent to using
__floordiv__ and __mod__; it should not be related to
__truediv__ (described below). Note that __pow__ should be
defined to accept an optional third argument if the ternary version of
the built-in pow function is to be supported.
Comment:
"I would love to contribute. How can I do it?" For now, just keep reviewing things! I doubt we'll turn this into a public wiki, but some kind of "edit through the web" support for trusted users is definitely on the drawing board.
Posted by Fredrik (2007-01-04)

Comment:
"These methods are called to implement the binary arithmetic operations..." It seems to me, this description should apply to all __something__ methods, not just __add__ (note "These").
OffTopic: I would love to contribute. How can I do it? Will you implement wiki someday?
Posted by Alexey Shamrin (2006-12-08)