pub(in path), pub(crate), pub(super), and pub(self)

In addition to public and private, Rust allows users to declare an item as visible only within a given scope. The rules for pub restrictions are as follows:

• pub(in path) makes an item visible within the provided path. path must be an ancestor module of the item whose visibility is being declared.
• pub(crate) makes an item visible within the current crate.
• pub(super) makes an item visible to the parent module. This is equivalent to pub(in super).
• pub(self) makes an item visible to the current module. This is equivalent to pub(in self) or not using pub at all.