public static function keyValMap($traversable, callable $keyFn, callable $valFn)
    {
        $map = [];
        foreach ($traversable as $item) {
            $map[$keyFn($item)] = $valFn($item);
        }

        return $map;
    }
public static function keyValMap($traversable, callable $keyFn, callable $valFn)
    {
        $map = [];
        foreach ($traversable as $item) {
            $map[$keyFn($item)] = $valFn($item);
        }

        return $map;
    }
@param mixed[]|Traversable $traversable

@return mixed[][]