val pair : ?eq:(('a * 'b) -> ('a * 'b) -> bool) -> 'a React.signal -> 'b React.signal -> ('a * 'b) React.signalval fst : ?eq:('a -> 'a -> bool) -> ('a * 'b) React.signal -> 'a React.signalval snd : ?eq:('a -> 'a -> bool) -> ('b * 'a) React.signal -> 'a React.signal