code: public function isValid($name, $isCustom)
      {
          if (!$isCustom) {
              return 1 === Preg::match('/^[a-z][a-z0-9_]*$/', $name);
          }
  
          return 1 === Preg::match('/^[A-Z][a-zA-Z0-9]*\/[a-z][a-z0-9_]*$/', $name);
      }
docs: @param string $name
  @param bool   $isCustom
  
  @return bool