code: function collapse_all(min_lines) {
    var elts = document.getElementsByTagName("div");
    for (var i=0; i<elts.length; i++) {
      var elt = elts[i];
      var split = elt.id.indexOf("-");
      if (split > 0)
        if (elt.id.substring(split, elt.id.length) == "-expanded")
          if (num_lines(elt.innerHTML) > min_lines)
            collapse(elt.id.substring(0, split));
    }
  }
docs: Collapse all blocks that mave more than `min_lines` lines.