hey, i would like to update keys from a `Pdef`

while its playing and tried to use `.set`

. any ideas?

```
(
SynthDef(\test, {
arg out=0, pan=0, amp=0.35, freq=150;
var env = Env.perc.kr(2);
var sig = Saw.ar(freq);
sig = Pan2.ar(sig, pan, amp * env);
Out.ar(out, sig);
}).add;
)
(
~f0 = Pstutter(3, Pseq([55],inf));
Pdef(\overtones,
Pbind(
\instrument,\test,
\multiply, Pseg(Pseq([1, 5],inf), Pseq([4, 1],inf), \linear),
\scale, Scale.minor(\just),
\numPartials, 5,
\freq, (Pn(Plazy {|event|
Pseries(1, 0.25, event[\numPartials])}, inf) * PL(\f0) * Pkey(\multiply)),
\dur, Pseq([0.25],inf).trace,
\amp,0.3,
)
).play;
)
Pdef(\overtones).set(\dur, 1); //doesnt work
```