inner::inner!

macro_rules! inner {
    ($x:expr, if $i:path, else |$e:ident| $b:block) => { ... };
    ($x:expr, if $i:path, else $b:block) => { ... };
    ($x:expr, else |$e:ident| $b:block) => { ... };
    ($x:expr, else $b:block) => { ... };
    ($x:expr, if $i:path) => { ... };
    ($x:expr) => { ... };
}

The inner! macro - see module level documentation for details.