ow be written as:\\n\\n```gren\\nwhen String.toInt \\\"42\\\" is\\n  Just num ->\\n    \\\"The string is a valid integer.\\\"\\n\\n  Nothing ->\\n    \\\"The string is _not_ a valid integer.\\\"\\n```\\n\\nThe rationale here is simply that `when is` reads better.\\n\\nA change with bigger impact is that custom types are now limited to either 0 or 1 parameters, where they previously could have many more.\\n\\nCode like this is no longer valid:\\n\\n```gren\\ntype Person = Person String Int\\n```\\n\\nIf you 