private function prepareNode(&$node, $key)
    {
        if (!isset($node[$key])) {
            $node[$key] = null;
        } elseif (!is_array($node[$key])) {
            $node[$key] = [$node[$key]];
        }
    }
private function prepareNode(&$node, $key)
    {
        if (!isset($node[$key])) {
            $node[$key] = null;
        } elseif (!is_array($node[$key])) {
            $node[$key] = [$node[$key]];
        }
    }
private function prepareNode ( & $ node , $ key ) { if ( ! isset ( $ node [ $ key ] ) ) { $ node [ $ key ] = null ; } elseif ( ! is_array ( $ node [ $ key ] ) ) { $ node [ $ key ] = [ $ node [ $ key ] ] ; } }
Prepares a value in the array at the given key.

If the key already exists, the key value is converted into an array.

@param array  $node Result node to modify
@param string $key  Key to add or modify in the node
Prepares a value in the array at the given key .