anchor.diff:      find_free_port([0]);
   find_free_port(Port) ->
       find_free_port([Port]).
  +
  +
  +-spec format(string(), list()) -> string().
  +format(FormatString, Items) ->
  +    lists:flatten(io_lib:format(FormatString, Items)).
  +
  +-spec exec(string()) -> pid().
  +exec(Cmd) ->
  +    _ = spawn(os, cmd, [Cmd]).
  
positive.code: init() ->
      case config:read(cloud_local_min_vms) of
          failed ->
              config:write(cloud_local_min_vms, 1),
              config:write(cloud_local_max_vms, ?PLUS_INFINITY);
          X -> X
      end,
  
negative.code: %%%% Helper methods
  %%%%%%%%%%%%%%%%%%%
  -spec find_free_port(comm_server:tcp_port() | [comm_server:tcp_port()] |
                       {From::comm_server:tcp_port(), To::comm_server:tcp_port()})
                      -> comm_server:tcp_port().
  find_free_port({From, To}) ->
      find_free_port(lists:seq(From, To));
  find_free_port([Port | Rest]) when is_integer(Port) andalso Port >= 0 andalso Port =< 65535 ->
  