KeyMap¶ $ wo 'KeyMap[f, <|a -> 1, b -> 2|>]' <|f[a] -> 1, f[b] -> 2|> The operator form KeyMap[f] applies to an association later. $ wo 'KeyMap[f][<|a -> 1, b -> 2|>]' <|f[a] -> 1, f[b] -> 2|>