@Marshall question re: https://github.com/mlochbaum/BQN/blob/f74d9223ef880f2914030c2375f680dcc7e8c92b/bqn.js#L12
if id.sh is falsy, why do [a,i]=id; a[i]=v; if only v is going to be returned the next line?
makin' some progress. prolly relax for rest of evening no hurry ty