'From Squeak3.1alpha of 5 February 2001 [latest update: #4281] on 23 August 2001 at 1:00:37 pm'! "Change Set: envRefix Date: 23 August 2001 Author: Bob Arning A revision of Henrik's change to answer correctly when the receiver is an Environment (modulo the compatibility hacks in Environment>>#at....) as well as returning the right answer in other cases."! !Dictionary methodsFor: 'testing' stamp: 'RAA 8/23/2001 12:56'! includesKey: key "Answer whether the receiver has a key equal to the argument, key." self at: key ifAbsent: [^false]. ^true! !