Lack of += and -= operators in Pyrex?

[Skip Montanaro]

I'm experimenting a bit with Pyrex and like it pretty well so far.
While converting a module from Python to Pyrex I noticed it complains
about the use of the += and -= assignment operators.  The fix is
obviously pretty trivial.  I didn't notice any mention in the Pyrex
docs as a difference between Python and Pyrex though.  Was I mistaken?

In case it makes any difference, the structure of the couple
statements I needed to change was

    obj.attr.subattr += self.attr

Thx,

Skip