code: function extractCategoryMap(oSentence) {
      var res = {};
      debuglog(debuglog.enabled ? ('extractCategoryMap ' + JSON.stringify(oSentence)) : '-');
      oSentence.forEach(function (oWord, iIndex) {
          if (oWord.category === IFMatch.CAT_CATEGORY) {
              res[oWord.matchedString] = res[oWord.matchedString] || [];
              res[oWord.matchedString].push({ pos: iIndex });
          }
      });
      utils.deepFreeze(res);
      return res;
  }
docs: Given a sentence, extact categories