C# generics syntax for multiple type parameter constraints [duplicate]

Possible Duplicate:
Generic methods and multiple constraints

I need a generic function that has two type constraints, each inheriting from a different base class. I know how to do this with one type:

void foo<T>() where T : BaseClass

However, I don’t know how to do this with two types:

void foo<TOne, TTwo>() where TOne : BaseOne // and TTwo : BaseTwo ???

How do you do this? (using .NET 2)