code: public function getLiteral($token)
      {
          $className = get_class($this);
          $reflClass = new \ReflectionClass($className);
          $constants = $reflClass->getConstants();
  
          foreach ($constants as $name => $value) {
              if ($value === $token) {
                  return $className . '::' . $name;
              }
          }
  
          return $token;
      }
docs: Gets the literal for a given token.
  
  @param integer $token
  
  @return string