Function printtable::write

pub fn write<H, I, T, U, V, W>(
    writer: W, 
    header: H, 
    mat: T
) -> Result<(), Error> where
    H: IntoIterator<Item = I>,
    I: ToString + Sized,
    T: IntoIterator<Item = U>,
    U: IntoIterator<Item = V>,
    V: ToString + Sized,
    W: Write,