If the next command from the command queue is anything but an actual
command, then the command is returned.
If the command is an
IOTCM command, then the following happens:
The given computation is applied to the command and executed. If an
abort command is encountered (and acted upon), then the computation is
interrupted, the persistent state and all options are restored, and
some commands are sent to the frontend. If the computation was not
interrupted, then its result is returned.