nom::pair!

macro_rules! pair(
  ($i:expr, $submac:ident!( $($args:tt)* ), $submac2:ident!( $($args2:tt)* )) => (
    {
      match $submac!($i, $($args)*) {
        $crate::IResult::Error(a)      => $crate::IResult::Error(a),
        $crate::IResult::Incomplete(i) => $crate::IResult::Incomplete(i),
        $crate::IResult::Done(i1,o1)   => {
          match $submac2!(i1, $($args2)*) {
            $crate::IResult::Error(a)      => $crate::IResult::Error(a),
            $crate::IResult::Incomplete(i) => $crate::IResult::Incomplete(i),
            $crate::IResult::Done(i2,o2)   => {
              $crate::IResult::Done(i2, (o1, o2))
            }
          }
        },
      }
    }
  );

  ($i:expr, $submac:ident!( $($args:tt)* ), $g:expr) => (
    pair!($i, $submac!($($args)*), call!($g));
  );

  ($i:expr, $f:expr, $submac:ident!( $($args:tt)* )) => (
    pair!($i, call!($f), $submac!($($args)*));
  );

  ($i:expr, $f:expr, $g:expr) => (
    pair!($i, call!($f), call!($g));
  );
);

pair!(I -> IResult<I,O>, I -> IResult<I,P>) => I -> IResult<I, (O,P)> pair(X,Y), returns (x,y)