anchor.diff:  domain(#var{prefix = Prefix})                          -> Prefix.
   
   state_member(#var{prefix = undefined, name = "PATH"})        -> "path";
  +state_member(#var{prefix = undefined, name = "CLIENT_IP"})   -> "client_ip";
   state_member(#var{prefix = undefined, name = "CLIENT_PORT"}) -> "client_port";
   state_member(#var{prefix = undefined, name = "SERVER_NAME"}) -> "server_name";
   state_member(#var{prefix = undefined, name = "SERVER_PORT"}) -> "server_port";
  
positive.code:     State#state{
        path = Value
      };
  set(State, #var{prefix = undefined, name = "SERVER_NAME"}, Value, undefined) ->
      State#state{
        server_name = Value
  
negative.code: %% -------------------------------------------------------------------
  
  domain(#var{prefix = undefined, name = "PATH"})        -> "request";
  domain(#var{prefix = undefined, name = "CLIENT_IP"})   -> "request";
  domain(#var{prefix = undefined, name = "CLIENT_PORT"}) -> "request";
  domain(#var{prefix = undefined, name = "SERVER_NAME"}) -> "request";
  domain(#var{prefix = undefined, name = "SERVER_PORT"}) -> "request";
  