How to remove nesting in an array?

Question

PHP

There is such an array:

Array 
( 
  [0] => Array 
  (
    [0] => 6 
    [1] => 10
    [2] => 59
    [3] => 175
  ) 
  [1] => Array 
  ( 
    [0] => 896712
    [1] => 898015
    [2] => 898018
  ) 
  [2] => Array 
  ( 
    [0] => 900000
    [1] => 900001
  ) 
)

You need to make it like this:

Array 
( 
  [0] => 6 
  [1] => 10
  [2] => 59
  [3] => 175
  [0] => 896712
  [1] => 898015
  [2] => 898018
  [0] => 900000
  [1] => 900001
)

Keys are not needed in principle. It is important that the values ​​are in the same array.

Answer 1

<?php
    $in = ;
    $out = [];
    array_walk_recursive($in, function($in) use (&$out) { $out[] = $in; });
    print_r($out);