package binary

import "io"

type Binary interface {
    WriteTo(w io.Writer) (int64, error)
}

func WriteOnto(b Binary, w io.Writer, n int64, err error) (int64, error) {
    if err != nil { return n, err }
    var n_ int64
    n_, err = b.WriteTo(w)
    return n+n_, err
}