Attribute Macro states

#[states]

Denotes which states will be used for the type-state pattern.

Usage: #[states(State1, State2, ...)]

What it does:

• defines the set of states that a type can transition between,
• generates marker structs for these states
• seals these traits and structs with TypeStateProtector trait for each state,
• provides the necessary struct_name information to #[require] macro

To save the users of this library from having to provide the name of the struct to each #[require] macro, #[states] macro handles that for you, providing the name of the struct to the #[require] macro behind the scenes.