docs: def youtube(keyword=None):
      """Open youtube.
  
      Args:
          keyword (optional): Search word.
      """
      if keyword is None:
          web.open('https://www.youtube.com/watch?v=L_mBVT2jBFw')
      else:
          web.open(quote('https://www.youtube.com/results?search_query={}'.format(keyword), RESERVED))