public void runCommand(String command) {
        for (Command x : commands) {
            if (x.isMine(command)) {
                String answer = x.execute();
                if (answer != null) {
                    output.println(answer);
                    output.flush();
                } else {
                    String error = x.getError();
                    if (error != null) {
                        output.println(error);
                        output.flush();
                    }
                }
                return;
            }

            String error = x.getError();
            if (error != null) {
                output.println(error);
                output.flush();
                return;
            }
        }
        output.println("illegal command");
        output.flush();
    }