d = [];
    for (var i = 0, n = elementNames.length; i < n; ++i) {
      var elementName = elementNames[i];
      if (!Object.hasOwnProperty.call(result, elementName)) {
        elementNamesNeeded.push(elementName);
      }
    }
    console.log('nNeededLast=%s, nNeeded=%d, result=%o',
                nNeededLast, elementNamesNeeded.length, result);
    if (elementNamesNeeded.length === nNeededLast) {
      // We made no progress last run.
      console.log('cannot place ' + elementNamesNeeded);
      eleme