macro_rules! assert_matches {
  ($expression:expr, $( $pattern:pat )|+ $( if $guard:expr )?) => {
    match $expression {
      $( $pattern )|+ $( if $guard )? => {}
      left => panic!(
        "assertion failed: (left ~= right)\n  left: `{:?}`\n right: `{}`",
        left,
        stringify!($($pattern)|+ $(if $guard)?)
      ),
    }
  }
}