C# code that trigger when sender is not a member of specific groups

Here is an example of C# code if you need to create a rule in the Crossware console for Exchange or M365, which will display a signature if the sender is not a member of one of the groups specified in the formula:

bool bIsFR;
bool bIsUK;

bIsFR = (!groupmember group="Grp TKM Administratif FR"  name="(!username!)"!) ?  true :  false;
bIsUK = (!groupmember group="Grp TKM Administratif UK"  name="(!username!)"!) ?  true :  false;

if(bIsFR || bIsUK){
    return false;
}
else{
    return true;
}