code: protected function update($key, $value = null, $group = null)
      {
          if ($key instanceof Attribute) {
              $value = $key->getValue();
              $group = $key->getMetaGroup();
              $key = $key->getMetaKey();
          }
  
          $this->get($key)->setValue($value);
          $this->get($key)->setMetaGroup($group);
  
          return $this;
      }
docs: Update existing attribute.
  
  @param  \Sofa\Eloquence\Metable\Attribute|string $key
  @param  mixed  $value
  @return $this