code: def signable(self, request, authheaders, response_body):
          
          nonce = authheaders["nonce"]
          timestamp = request.get_header("x-authorization-timestamp")
          try:
              body_str = response_body.decode('utf-8')
          except:
              body_str = response_body
          return '{0}\n{1}\n{2}'.format(nonce, timestamp, body_str)
docs: Creates the signable string for a response and returns it.
  
          Keyword arguments:
          request -- A request object which can be consumed by this API.
          authheaders -- A string-indexable object which contains the headers appropriate for this signature version.
          response_body -- A string or bytes-like object which represents the body of the response.