anchor.diff:    db_ops/1,
     basic_op/1,
     update_doc/1,
  +  delete_doc_without_revision/1,
     update_with/1,
     async_update/1,
     bad_doc/1,
  
positive.code:   {ok, <<"a">>, _RevId2} = barrel_httpc:delete(db(Config), <<"a">>, [{rev, RevId2}]),
    {error, not_found} = barrel_httpc:get(db(Config), <<"a">>, []),
    {ok, <<"a">>, _RevId3} = barrel_httpc:post(db(Config), Doc, []).
  
  update_with(Config) ->
    Doc = #{ <<"id">> => <<"a">>, <<"v">> => 1},
  
negative.code:     db_ops,
      basic_op,
      update_doc,
      delete_doc_without_revision,
      update_with,
      async_update,
      bad_doc,
  