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

@ildjarn deserves the credit here for answering first, but I'm submitting the answer here so it can be accepted.

The F# equivalent of the C# is keyword is :?. For example:

let cat = Animal()
if cat :? Animal then
    printfn "cat is an animal."
else
    printfn "cat is not an animal."