'From Squeak3.10beta of 22 July 2007 [latest update: #7137] on 15 November 2007 at 9:48:18 pm'! "Change Set: CharacterSetComplement-M6367-nice-hashPatch Date: 15 November 2007 Author: nice Reported by Boris Gaertner: CharacterSetComplement>> hash sends the message bitXOr: which is nowhere defined. I think the correct writing of the message is bitXor: So, this is the patch..."! !CharacterSetComplement methodsFor: 'comparing' stamp: 'nice 11/1/2007 19:39'! hash ^ absent hash bitXor: self class hash! !