Array Keys and Values in PHP

Задание 1

Given an array:

php<?php
  $arr = ['a' => 1, 'b' => 2, 'c' => 3];
?>

Get the array of keys of this array.

Задание 2

Given an array:

php<?php
  $arr = ['a' => 1, 'b' => 2, 'c' => 3];
?>

Get the array of values of this array.