Pwhile while a condition holds,  repeatedly embed  stream

superclass: FuncFilterPattern

Pwhile(func, pattern)

(

var a, b, z = true;

a = Pwhile({ z }, Pseq(#[1, 2, 3]));

x = a.asStream;

9.do({ x.next.postln; });

z = false;

x.next.postln;

)