Switch off and on a fix command

Dear LAMMPS users,

How can i switch OFF and ON a fix command per time step ?!


Don’t know what switch on/off means.
When a fix command is defined it operates
during a run. The only way to turn it off
for some portion of the run would be
to break the run into smaller pieces (on segment,
off segment), and unfix, then re-define the fix.

You could do this in a loop, or probably using
the run every command.