code: public function setMetaGroup($group = null)
      {
          if (!preg_match('/^[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*$/', $group) && $group !== null) {
              throw new InvalidArgumentException("Provided group [{$group}] is not valid variable name.");
          }
  
          $this->attributes['meta_group'] = $group;
      }
docs: Set group of the meta attribute.
  
  @param string $group
  
  @throws \InvalidArgumentException