Lib.rs

When you create a Rust function expecting an optional reference, use Option<&Foo> rather than &Option<Foo>.

/// An optional shared reference to a `Maybe` type
fn optional(good: Option<&Maybe>) { /* ← do this */ }

/// A reference to an `Option` exclusively owning the `Maybe` instance
fn optional(bad: &Option<Maybe>) { /* ← not this */ }

Both options happen to have the same representation in memory, but Option<&T> is easier to work with, and is more universal. This is because Option<&T> can be created on the fly from from T, &T, and Option<T> or &Option<T> (via .as_ref()), but borrowing &Option<T> requires having specifically Option<T>.