def _process_content_range(content_range):
    """Convert a 'Content-Range' header into a length for the response.

    Helper for :meth:`Response.length`.

    :type content_range: str
    :param content_range: the header value being parsed.

    :rtype: int
    :returns: the length of the response chunk.
    """
    _, _, range_spec = content_range.partition(' ')
    byte_range, _, _ = range_spec.partition('/')
    start, _, end = byte_range.partition('-')
    return int(end) - int(start) + 1