code: def compare(self, first, second, chamber, type='votes', congress=CURRENT_CONGRESS):
          
          check_chamber(chamber)
          path = "members/{first}/{type}/{second}/{congress}/{chamber}.json"
          path = path.format(first=first, second=second, type=type,
                             congress=congress, chamber=chamber)
          return self.fetch(path)
docs: See how often two members voted together in a given Congress.
          Takes two member IDs, a chamber and a Congress number.