# What SimpleKeyGenerator actually puts in the map

cache "shapes" after three calls with 0, 1 and 2 arguments:

  cache "shapes":
    key abc                    [String]   ->  one:abc
    key SimpleKey [abc, 7]     [SimpleKey]   ->  two:abc:7
    key SimpleKey []           [SimpleKey]   ->  zero

Zero arguments  -> the SimpleKey.EMPTY constant, printed as []
One argument    -> that argument itself, unwrapped
Two or more     -> a SimpleKey holding all of them

The method name and the declaring class appear nowhere in the key.