id: no-flag-argument
valid:
  # boolean default but never branched on (merely forwarded / unused)
  - |
    function render(node, verbose = false) {
      return compactPrint(node, verbose);
    }
  # branches, but on a non-flag (property), not a boolean-default param
  - |
    function render(node, opts) {
      if (opts.pretty) { return prettyPrint(node); }
      return compactPrint(node);
    }
  # boolean default, but the branch is on a DIFFERENT variable
  - |
    function render(node, debug = true) {
      if (somethingElse) { return 1; }
      return 2;
    }
invalid:
  - |
    function render(node, pretty = false) {
      if (pretty) { return prettyPrint(node); }
      return compactPrint(node);
    }
  - |
    class C {
      draw(shape, filled = false) {
        if (filled) return this.fill(shape);
        return this.stroke(shape);
      }
    }
  - |
    const handle = (req, deferred = false) => {
      if (!deferred) return now(req);
      return defer(req);
    };