code: function createNamedToNumberedLookup(items, radix) {
          var i, entity, lookup = {}, base10, base16;
          items = items.split(',');
          radix = radix || 10;
          // Map from named to numbered entities.
          for (i = 0; i < items.length; i += 2) {
              entity = '&' + items[i + 1] + ';';
              base10 = parseInt(items[i], radix);
              lookup[entity] = '&#'+base10+';';
          }
          //FF and IE need to create a regex from hex values ie &nbsp; == \xa0
          lookup["\\xa0"] = '&#160;';
          return lookup;
      }
docs: helper function to map named to numbered entities