//! A trait for accessing I/O ports.
/// A helper trait that implements the actual port operations.
///
/// On x86, I/O ports operate on either `u8` (via `inb`/`outb`), `u16` (via `inw`/`outw`),
/// or `u32` (via `inl`/`outl`). Therefore this trait is implemented for exactly these types.