code: def get_auth_server_name(host_override=None, port_override=None, protocol='https'):
      
      if host_override is not None or port_override is not None:
          if host_override is None or port_override is None:
              raise exceptions.DXError("Both host and port must be specified if either is specified")
          return protocol + '://' + host_override + ':' + str(port_override)
      elif APISERVER_HOST == 'stagingapi.dnanexus.com':
          return 'https://stagingauth.dnanexus.com'
      elif APISERVER_HOST == 'api.dnanexus.com':
          return 'https://auth.dnanexus.com'
      elif APISERVER_HOST == 'stagingapi.cn.dnanexus.com':
          return 'https://stagingauth.cn.dnanexus.com:7001'
      elif APISERVER_HOST == 'api.cn.dnanexus.com':
          return 'https://auth.cn.dnanexus.com:8001'
      elif APISERVER_HOST == "localhost" or APISERVER_HOST == "127.0.0.1":
          if "DX_AUTHSERVER_HOST" not in os.environ or "DX_AUTHSERVER_PORT" not in os.environ:
              err_msg = "Must set authserver env vars (DX_AUTHSERVER_HOST, DX_AUTHSERVER_PORT) if apiserver is {apiserver}."
              raise exceptions.DXError(err_msg.format(apiserver=APISERVER_HOST))
          else:
              return os.environ["DX_AUTHSERVER_HOST"] + ":" + os.environ["DX_AUTHSERVER_PORT"]
      else:
          err_msg = "Could not determine which auth server is associated with {apiserver}."
          raise exceptions.DXError(err_msg.format(apiserver=APISERVER_HOST))
docs: Chooses the auth server name from the currently configured API server name.
  
      Raises DXError if the auth server name cannot be guessed and the overrides
      are not provided (or improperly provided).