def make_range_string(start, stop=None):
    """Create a byte range specifier in accordance with RFC-2616.

    Parameters
    ----------
    start: int
        The start of the byte range

    stop: int, optional
        The end of the byte range.  If unspecified, indicates EOF.

    Returns
    -------
    str
        A byte range specifier.

    """
    if stop is None:
        return 'bytes=%d-' % start
    return 'bytes=%d-%d' % (start, stop)
