def _make_url(raw, sig, quick=True):
    """ Return usable url. Set quick=False to disable ratebypass override. """
    if quick and 'ratebypass=' not in raw:
        raw += '&ratebypass=yes'
    if 'signature=' not in raw:
        if sig is None:
            raise IOError('Error retrieving url')
        raw += '&signature=' + sig
    return raw
