code: function(o, readOnly) {
          var uid;
          if (!o) {
              return o;
          }
          
          // IE generates its own unique ID for dom nodes
          // The uniqueID property of a document node returns a new ID
          if (o.uniqueID && o.nodeType && o.nodeType !== 9) {
              uid = o.uniqueID;
          } else {
              uid = (typeof o === 'string') ? o : o._yuid;
          }
  
          if (!uid) {
              uid = this.guid();
              if (!readOnly) {
                  try {
                      o._yuid = uid;
                  } catch(e) {
                      uid = null;
                  }
              }
          }
          return uid;
      }
docs: Returns a guid associated with an object.  If the object
  does not have one, a new one is created unless readOnly
  is specified.
  @method stamp
  @param o The object to stamp
  @param readOnly {boolean} if true, a valid guid will only
  be returned if the object has one assigned to it.
  @return {string} The object's guid or null