a simple attribute toggle script that you can use as a shelf button or in the script editor

Maya_Attribute_Toggle.mel

// ***************************************************
//                       README
// ***************************************************
// ***************************************************
// As the examples show, put your arrtribute IDs in 
// the list after line 16 between quotation marks like
// these: "" and with a coma , at the end. EXCEPT for 
// the very last element of the list.
// If you don't know your attribute id, open your 
// script editor, clear the top-part history, and 
// toggle the attribute manually. The script history 
// should show something like :
//        setAtt "yourObject.attribute"
// Copy what's between the quotes.

string $attrList[] = {
    "myObject.holdOut",
    "myOtherObject.holdOut"
};
for ($i = 0; $i < `size $myAttr`; $i++){
    setAttr $attrList[$i] (!`getAttr $attrList[$i]`);
}

// Written by Loïc "L0Lock" DAUTRY
// Source:
// https://gist.github.com/L0Lock/c1330ee50b0775b23b34ec969f73906e

As the examples show, put your attribute IDs in the list after line 8, between quotation marks like these: "" and with a coma , at the end, except for the very last element of the list.
If you don't know your attribute id, open your script editor, clear the top-part history, and toggle the attribute manually. The script history should show something like : setAtt "yourObject.attribute"
Copy what's between the quotes.