src/Marando/AstroDate/Traits/FormatTrait.php
private function format_y(&$str) {
    if (strstr($str, '%y'))
      $str = str_replace(
              '%y', substr($this->year, strlen($this->year) - 2, 2), $str);
  }
private function format_y(&$str) {
    if (strstr($str, '%y'))
      $str = str_replace(
              '%y', substr($this->year, strlen($this->year) - 2, 2), $str);
  }
A two digit representation of a year
@param type $str