Macro builder_send

macro_rules! builder_send {
    {
        #[$builder:ident] $typ:ty,
        $(#[$out_res:ident])? $out_type:ty
    } => { ... };
    { @send, $typ:ty, $out_type:ty } => { ... };
    { @send:discard_result, $typ:ty, $out_type:ty } => { ... };
    { @send:flatten_result, $typ:ty, $out_type:ty } => { ... };
    { @send:rate_limited, $typ:ty, $out_type:ty } => { ... };
    { @send:no_send, $typ:ty, $out_type:ty } => { ... };
}

Helper macros for implementing the send function on the builder

Introduced in v3.0.0-alpha.1