/// Decodes a custom message to `CustomMessageType`. If the given message type is known to the
/// implementation and the message could be decoded, must return `Ok(Some(message))`. If the
/// message type is unknown to the implementation, must return `Ok(None)`. If a decoding error
/// Decodes a custom message to `CustomMessageType`. If the given message type is known to the
/// implementation and the message could be decoded, must return `Ok(Some(message))`. If the
/// message type is unknown to the implementation, must return `Ok(None)`. If a decoding error
/// Defines a type identifier for sending messages over the wire.
///
/// Messages implementing this trait specify a type and must be [`Writeable`].
/// Defines a type identifier for sending messages over the wire.
///
/// Messages implementing this trait specify a type and must be [`Writeable`].