public void addCommand(@NonNull String command, int code, @Nullable OnCommandResultListener resultListener) {
      addCommand(new String[]{command}, code, resultListener);
    }
<p>Add a command to execute, with a callback to be called on completion</p>

<p>The thread on which the callback executes is dependent on various factors, see {@link Shell.Interactive}
for further details</p>

@param command
    Command to execute
@param code
    User-defined value passed back to the callback
@param resultListener
    Callback to be called on completion
imitate/src/main/java/com/engineer/imitate/shell/Shell.java