What is this data type?

[onenonly]

function testMe(funcName){
                
    return new funcName();
                
}

I have a movieclip linkage name waterTile.
i want to dynamically change function name

Example
testMe(waterTile);

it will return waterTile();

what is the data type of funcName?

[5TonsOfFlax]

Class.

And it's not a function name.