 [det]el_history(+In:stream, 
?Action)Perform a generic action on the history. This provides an incomplete 
interface to
[det]el_history(+In:stream, 
?Action)Perform a generic action on the history. This provides an incomplete 
interface to history() from libedit. Supported actions are:
- clear
- Clear the history.
- setsize(+Integer)
- Set size of history to size elements.
- setunique(+Boolean)
- Set flag that adjacent identical event strings should not be entered 
into the history.