lsym_rbracket
case lsym_rbracket: process_rbracket(); break;
ps.want_blank = lsym != lsym_rparen && lsym != lsym_rbracket;
|| ps.prev_lsym == lsym_rbracket
ps.prev_lsym == lsym_rbracket)
case ']': lsym = lsym_rbracket; next_unary = false; break;
ps.prev_lsym == lsym_rbracket) {