// i must point at the (possibly imaginary) closing bracket (any of the 2 types, not type parameters)
// index returned is index of opening bracket
static int findBeginningOfBracketPart(LS cnc, int i) {
  int j = i-2, level = 1;
  while (j > 0) {
    if (eqOneOf(cnc.get(j), "}", ")")) ++level;
    else if (eqOneOf(cnc.get(j), "{", "(")) --level;
    if (level == 0)
      ret j;
    j -= 2;
  }
  return -1;
}