php-ds / polyfill

     * @param callable $callback Accepts two arguments: key and value, should

     *                           return what the updated value will be.

     */

    public function apply(callable $callback): Map

    {

        foreach ($this->pairs as &$pair) {

            $pair->value = $callback($pair->key, $pair->value);

        }

        return $mapped;

    }

    /**

     * @inheritDoc

     *

     * @return Map

     */

    public function map(callable $callback): Map

    {

        $mapped = new self();

        foreach ($this->pairs as $pair) {

            $mapped[$pair->key] = $callback($pair->key, $pair->value);

        }

        return $mapped;

    }

    /**

     * Returns a sequence of pairs representing all associations.