public function substr($start, $length=null)
    {
        return $this->newInstance(mb_substr($this->toString(), $start, $length, $this->getEncoding()));
    }
public function substr($start, $length=null)
    {
        return $this->newInstance(mb_substr($this->toString(), $start, $length, $this->getEncoding()));
    }
public function substr ( $ start , $ length = null ) { return $ this -> newInstance ( mb_substr ( $ this -> toString ( ) , $ start , $ length , $ this -> getEncoding ( ) ) ) ; }
Return a substring of value
@param int $start
@param int $length
@return \PerrysLambda\StringProperty
Return a substring of value