anchor.diff:    | DescribeRepl -> run_describe_repl st
     | GenericError message -> run_generic_error st message
     | ProtocolViolation query -> run_protocol_violation st query
  +  | Segment c -> run_segment st c
     | VfsAdd (fname, contents) -> run_vfs_add st fname contents
     | Push pquery -> run_push st pquery
     | Pop -> run_pop st
  
positive.code:   else
      let st' = pop_repl st in
      ((QueryOK, JsonNull), Inl st')
  
  let collect_errors () =
    let errors = FStar.Errors.report_all() in
    FStar.Errors.clear ();
    errors
  
  (** Compute and load all dependencies of `filename`.
  
  
negative.code: | Exit
  | DescribeProtocol
  | DescribeRepl
  | Segment of string (* File contents *)
  | Pop
  | Push of push_query
  | VfsAdd of option<string> (* fname *) * string (* contents *)
  