Function json_decode::map2

pub fn map2<'a, F, _1, _2, NewDecodesTo>(
    func: F, 
    _1: BoxDecoder<'a, _1>, 
    _2: BoxDecoder<'a, _2>
) -> BoxDecoder<'a, NewDecodesTo> where
    F: Fn(_1, _2) -> NewDecodesTo + 'a + Send + Sync,
    NewDecodesTo: 'a,
    _1: 'a,
    _2: 'a,