Functions: unknown parameter types and getting around them

If i have a function and im strict typing: such as

private var x:Number

public function foo(y:Number){
x = y;
}

public function foo2(y:MovieClip){
x = y;
}

obviously the second doesnt work because y is a movieclip and x is a number, but i want to be able to set x to whatever type is being passed in.

is this possible??