Function json_decode::and_then

pub fn and_then<'a, F, T, NewDecodesTo>(
    func: F, 
    d: BoxDecoder<'a, T>
) -> BoxDecoder<'a, NewDecodesTo> where
    F: Fn(T) -> BoxDecoder<'a, NewDecodesTo> + 'a + Send + Sync,
    NewDecodesTo: 'a,
    T: 'a,