docs: def asnum(number, limit=None, return_format=None):
      """Returns a summary of the information our database holds for a
      particular ASNUM (similar to /asdetailsascii.html) with return limit.
  
      :param limit: number of records to be returned (max 2000)
      """
      uri = 'asnum/{number}'.format(number=number)
      if limit:
          uri = '/'.join([uri, str(limit)])
      return _get(uri, return_format)