[Tutor] Why next vs. __next__ ?

[python at bdurham.com]

Is there a reason why generators have a special method named "next" vs.
"__next__"?

All other Python's special names have the double underscore
prefix/suffix.
http://docs.python.org/ref/specialnames.html

Are there other special names like "next" that don't have the double
underscore delimiters?

Thanks!
Malcolm