code: def buid():
      
      if six.PY3:  # pragma: no cover
          return urlsafe_b64encode(uuid.uuid4().bytes).decode('utf-8').rstrip('=')
      else:  # pragma: no cover
          return six.text_type(urlsafe_b64encode(uuid.uuid4().bytes).rstrip('='))
docs: Return a new random id that is exactly 22 characters long,
      by encoding a UUID4 in URL-safe Base64. See
      http://en.wikipedia.org/wiki/Base64#Variants_summary_table
  
      >>> len(buid())
      22
      >>> buid() == buid()
      False
      >>> isinstance(buid(), six.text_type)
      True