Php Remove duplicates from array and also remove all nulls

$array = array(1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20);

function removeDuplicates($array) {
  $array = array_unique($array);
  $array = array_filter($array, function($value) {
    return $value !== null;
  });
  return $array;
}

//example
$result = removeDuplicates($array);

//output
print_r($result); //Array ( [0] => 1 [1] => 2 [2] => 3 [3] => 4 [4] => 5 [5] => 6 [6] => 7 [7] => 8 [8] => 9 [9] => 10 [10] => 11 [11] => 12 [12] => 13 [13] => 14 [14] => 15 [15] => 16 [16] => 17 [17] => 18 [18] => 19 [19] => 20 )