Repeated Function Composition

Stream: Is there code for X?

[Shimon Schlessinger]

I can't find in the documentation how to repeatedly compose a function in the documentation.
For example, there is no way to rewrite

(f ∘ f ∘ f ) x = (f ^ 3)  x --or maybe in some other notation because the RHS is interpreted as (f x) ^ 3

and no already defined way for arbitrarily many compositions.
Does this type of thing already exist?

[Adam Topaz]

The notation is f ^ [37] x

[Junyan Xu]

docs#nat.iterate
It would be nice if notation declarations show up in the docs.

[Eric Wieser]

^ 3 works too if you use docs#function.End