src/Marando/AstroDate/Traits/FormatTrait.php
private function format_u(&$str) {
    if (strstr($str, '%u')) {
      $u   = substr($this->micro, 0, 3);
      $str = str_replace('%u', str_pad($u, 3, '0', STR_PAD_LEFT), $str);
    }
  }
private function format_u(&$str) {
    if (strstr($str, '%u')) {
      $u   = substr($this->micro, 0, 3);
      $str = str_replace('%u', str_pad($u, 3, '0', STR_PAD_LEFT), $str);
    }
  }
Milliseconds
@param type $str