1.221.2 WeakValueLookupTable: hacks

at: key ifAbsent: aBlock

Answer the value associated to the given key, or the result of evaluating aBlock if the key is not found

at: key ifPresent: aBlock

If aKey is absent, answer nil. Else, evaluate aBlock passing the associated value and answer the result of the invocation

includesKey: key

Answer whether the receiver contains the given key.