n:=1; do(30){ print(n.num1s,","); n*=3 } println();

println("evil: ",[0..].filter(30,fcn(n){ n.num1s.isEven }).concat(","));

// now, as an iterator aka lazy:
println("odious: ",(0).walker(*).tweak(   // 0,1,2,3,4... iterator
   fcn(n){ if(n.num1s.isEven) Void.Skip else n }).walk(30).concat(","));