Macro wrap_with

macro_rules! wrap_with {
    ($wrapper:ident >> fn $name:ident ($($arg:ident : $argtype:ty),*) -> $ret:ty = $body:expr) => { ... };
    ($wrapper:ident -> $before_block_res:ident : $before_block_ty:ty; >> fn $name:ident ($($arg:ident : $argtype:ty),*) -> $ret:ty = $body:expr) => { ... };
    ($wrapper:ident -> mut $before_block_res:ident : $before_block_ty:ty; >> fn $name:ident ($($arg:ident : $argtype:ty),*) -> $ret:ty = $body:expr) => { ... };
}