Grammar: why no ^= operator?

[Jeroen Demeyer <jdemeyer@cage.ugent.be>]

Hello list,

I noticed that GP does not have the ^= operator, so I propose to add 
that operator, in analogy with +=, /= and others...
It's clear what it should do:

gp> x=2
%1 = 2
gp> x^=7
%2 = 128

Cheers,
Jeroen.