\e
default(breakloop,1)
my(bound=100,step=20,halt=41); check(B)=
{
  my(bi=[B^2]);
  for(i=1,bound,
    my(p=i+step,N=p^2);
    if(i==halt,error("check:",N)))
}
check(1000);
[bound, step, halt, i, p, N, bi, B]
break
[bound, step, halt, i, p, N, bi, B]
my(p=120);for(i=1,100,1/0)
[p,i]
break
