F# equivalent of `is` keyword in C#?

Question

My first F# day. If I have this:

let cat = Animal()

Now how do I check at later stage if cat is Animal

Answer 1

For demonstration only (don't define an is function):

let is<'T> (x: obj) = x :? 'T

type Animal() = class end
type Cat() = inherit Animal()

let cat = Cat()
cat |> is //true