code: def set_host(self, host):
          
          if host[-1] == '/':
              host = host[:-1]
  
          self.host = host
          return self
docs: Set the host for a lightning server.
  
          Host can be local (e.g. http://localhost:3000), a heroku
          instance (e.g. http://lightning-test.herokuapp.com), or
          a independently hosted lightning server.