code: function(param) {
          if(!param || !($.type(param) == 'string')) return function() { return true; };
          var props = param.split(" ");
          return function(elem) {
              for(var i=0; i<props.length; i++) { 
                if(elem[props[i]]) { 
                  return false; 
                }
              }
              return true;
          };
      }
docs: /*
  filter
  
  For internal use only. Provides a filtering function based on flags.