Macro prepare_io 

macro_rules! prepare_io {
    (@inner ($dol:tt) $scanner:expr, $writer:expr) => { ... };
    (buffered; $reader:expr, $writer:expr $(,)?) => { ... };
    ($reader:expr, $writer:expr $(,)?) => { ... };
}

Prepare sc!, sv!, pp!, and dg! with fast I/O for the supplied reader and writer. prepare_io!(buffered; reader, writer) reads incrementally for large numeric inputs. Every read must satisfy FastInput’s token requirements.