How to add multiple assignment groups in single Assignment rule using script

Hi,

I have created an assignment rule and added one group(A) to Assigned to Group using a script.

if(condition ='true'){

current.assignment_group.setDisplayValue("A");

}

The above code is working fine.

Now I have a requirement where need to add three groups(A, B & C) in the Group field using the script.

Something like this: 

if(condition ='true'){

current.assignment_group.setDisplayValue("A;B;C");

}

is this possible or is there any workaround for this?