Each command returns a tuple: ``(type, [data, ...])`` where *type* is usually ``'OK'`` or ``'NO'``, and *data* is either the text from the command response, or mandated results from the command. Each *data* is either a ``bytes``, or a tuple. If a tuple, then the first part is the header of the response, and the second part contains the data (ie: 'literal' value).