Function recursion_guard 

pub fn recursion_guard(
    depth: usize,
    f: impl FnOnce(usize) -> (usize, Option<usize>),
) -> (usize, Option<usize>)

👎Deprecated: use try_recursion_guard instead

Protects against potential infinite recursion when calculating size hints due to indirect type recursion.

When the depth is not too deep, calls f with depth + 1 to calculate the size hint.

Otherwise, returns the default size hint: (0, None).

This method is deprecated. Users should instead implement try_size_hint and use try_recursion_guard