code: function(feature) {
          for (var i=0, len=this.fids.length; i<len; i++) {
              var fid = feature.fid || feature.id;
              if (fid == this.fids[i]) {
                  return true;
              }
          }
          return false;
      }
docs: APIMethod: evaluate
  evaluates this rule for a specific feature
  
  Parameters:
  feature - {<OpenLayers.Feature>} feature to apply the rule to.
  For vector features, the check is run against the fid,
  for plain features against the id.
  
  Returns:
  {Boolean} true if the rule applies, false if it does not