Macro ghost_actor::ghost_chan

macro_rules! ghost_chan {
    (
        name: $name:ident,
        error: $error:ty,
        api: { $( $req_name:ident :: $req_fname:ident ( $doc:expr, $req_type:ty, $res_type:ty ) ),* }
    ) => { ... };
    (
        name: $name:ident,
        error: $error:ty,
        api: { $( $req_name:ident :: $req_fname:ident ( $doc:expr, $req_type:ty, $res_type:ty ) ),*, }
    ) => { ... };
    (
        name: pub $name:ident,
        error: $error:ty,
        api: { $( $req_name:ident :: $req_fname:ident ( $doc:expr, $req_type:ty, $res_type:ty ) ),*, }
    ) => { ... };
    (
        name: pub $name:ident,
        error: $error:ty,
        api: { $( $req_name:ident :: $req_fname:ident ( $doc:expr, $req_type:ty, $res_type:ty ) ),* }
    ) => { ... };
    ( @inner
        ($($vis:tt)*), $name:ident, $error:ty,
        $( $doc:expr, $req_name:ident, $req_fname:ident, $req_type:ty, $res_type:ty ),*
    ) => { ... };
    ( @inner_protocol
        ($($vis:tt)*), $name:ident, $error:ty,
        $( $doc:expr, $req_name:ident, $req_fname:ident, $req_type:ty, $res_type:ty ),*
    ) => { ... };
    ( @inner_helper_sender
        $sendf:ident, $doc:expr, $req_fname:ident, (), $res_type:ty, $error:ty
    ) => { ... };
    ( @inner_helper_sender
        $sendf:ident, $doc:expr, $req_fname:ident, $req_type:ty, $res_type:ty, $error:ty
    ) => { ... };
    ( @inner_send_trait
        ($($vis:tt)*), $name:ident, $error:ty,
        $( $doc:expr, $req_name:ident, $req_fname:ident, $req_type:ty, $res_type:ty ),*
    ) => { ... };
}

GhostChan provides a basis for constructing GhostChannels and eventually GhostActors. GhostChan provides differentiated constructor functions, that generate appropriate input and async await output types.