function killAttrs(model, attrs) {
  for (var i = 0; i < attrs.length; i++) {
    delete model[attrs[i]];
  }
}
function killAttrs(model, attrs) {
  for (var i = 0; i < attrs.length; i++) {
    delete model[attrs[i]];
  }
}
function killAttrs ( model , attrs ) { for ( var i = 0 ; i < attrs . length ; i ++ ) { delete model [ attrs [ i ] ] ; } }
remove attributes from a model
remove attributes from a model