code: def validate_proxies_config(cls, proxies):
          
          for name, proxy in six.iteritems(proxies):
              if "port" not in proxy:
                  raise ValueError("No port defined for proxy %s" % name)
              if "upstreams" not in proxy:
                  raise ValueError(
                      "No upstreams defined for proxy %s" % name
                  )
              for upstream in proxy["upstreams"]:
                  if "host" not in upstream:
                      raise ValueError(
                          "No host defined for upstream in proxy %s" % name
                      )
                  if "port" not in upstream:
                      raise ValueError(
                          "No port defined for upstream in proxy %s" % name
                      )
docs: Specific config validation method for the "proxies" portion of a
          config.
  
          Checks that each proxy defines a port and a list of `upstreams`,
          and that each upstream entry has a host and port defined.