src/Arrays.php
public static function flatten(array $value) : array
    {
        $result = [];

        array_walk_recursive(
            $value,
            function ($item) use (&$result) {
                $result[] = $item;
            }
        );

        return $result;
    }
public static function flatten(array $value) : array
    {
        $result = [];

        array_walk_recursive(
            $value,
            function ($item) use (&$result) {
                $result[] = $item;
            }
        );

        return $result;
    }
public static function flatten ( array $ value ) : array { $ result = [ ] ; array_walk_recursive ( $ value , function ( $ item ) use ( & $ result ) { $ result [ ] = $ item ; } ) ; return $ result ; }
Given a multi-dimensional array, flatten the array to a single level.

The order of the values will be maintained, but the keys will not.

For example, given the array [[1, 2], [3, [4, 5]]], this would result in the array [1, 2, 3, 4, 5].

@param array $value The array to flatten.

@return array The single-dimension array.
Given a multi - dimensional array flatten the array to a single level .