code: public function isActive($name, Context $context)
      {
          // Disable features which aren't whitelisted
          if ($this->mode === self::WHITELIST && !in_array($name, $this->features, true)) {
              return false;
          }
  
          // Disable features which are blacklisted
          if ($this->mode === self::BLACKLIST && in_array($name, $this->features, true)) {
              return false;
          }
  
          // Disable if non cookie exists
          if (!array_key_exists($this->name, $_COOKIE)) {
              return false;
          }
  
          // Enable, if feature is set in cookie
          return in_array($name, array_map('trim', explode($this->separator, $_COOKIE[$this->name])), true);
      }
docs: {@inheritdoc}