A UGen that, when triggered, frees enclosing synth. It frees the enclosing
synth when the input signal crosses from non-positive to positive.
Note that if the trigger is initially high the UGen will not react. For
example, FreeSelf.kr("foo".kr) will not work if the control is initially 1 .
A work-around is to wrap the input in this case in a Trig object:
FreeSelf.kr(Trig.kr("foo".kr)) . This is most likely a bug.
This UGen outputs its input signal for convenience.
the input signal which will trigger the action.