Macro mm0b_parser::make_index_trait

macro_rules! make_index_trait {
    ([< $($lft : lifetime), * >, $ty : ident, $trait : ident, $notrait : ident, $f
  : ident, $f_mut : ident] $($fns : item) *) => { ... };
}

Constructs a new trait for accessing a subcomponent of the index data, with automatic impls for (), (A, B) and the subcomponent itself.