// not including <> as they are ambiguous (< is also a comparison operator)
static S testBracketHygiene_op    = "([{";
static S testBracketHygiene_close = ")]}";

static bool testBracketHygiene(S s) {
  ret testBracketHygiene(s, testBracketHygiene_op, testBracketHygiene_close, null);
}

static bool testBracketHygiene(S s, Var<S> msg) {
  ret testBracketHygiene(s, testBracketHygiene_op, testBracketHygiene_close, msg);
}

static bool testBracketHygiene(S s, S op, S close, Var<S> msg) {
  Pair<Int, S> p = testBracketHygiene2(s, op, close);
  if (p == null) {
    if (msg != null) msg.set("Hygiene OK!");
    true;
  }
  if (msg != null) msg.set(p.b);
  false;
}

Began life as a copy of #1003920