Macro otter_api_tests::want_let

macro_rules! want_let {
    { $($variant:ident)::+($binding:pat) = $input:expr;
    else ? $($d:expr),*; $($otherwise:tt)*
  } => { ... };
    { $($variant:ident)::+($binding:pat) = $input:expr;
    else $($otherwise:tt)*
  } => { ... };
}