code: public function contributor($username)
      {
          $this->username = $username;
          $this->pageFile = 'page.json';
          $this->seoFile = 'seo.json';
          if (null !== $this->username) {
              $this->pageFile = $this->seoFile = $this->username . '.json';
          }
  
          return $this;
      }
docs: Sets the page contributor
  @param string $username
  
  @return $this