Get response content and headers from a discharge macaroons error.

    @param macaroon may hold a macaroon that, when discharged, may
    allow access to a service.
    @param path holds the URL path to be associated with the macaroon.
    The macaroon is potentially valid for all URLs under the given path.
    @param cookie_suffix_name holds the desired cookie name suffix to be
    associated with the macaroon. The actual name used will be
    ("macaroon-" + CookieName). Clients may ignore this field -
    older clients will always use ("macaroon-" + macaroon.signature() in hex)
    @return content(bytes) and the headers to set on the response(dict).

def discharge_required_response(macaroon, path, cookie_suffix_name,
                                message=None):
    ''' Get response content and headers from a discharge macaroons error.

    @param macaroon may hold a macaroon that, when discharged, may
    allow access to a service.
    @param path holds the URL path to be associated with the macaroon.
    The macaroon is potentially valid for all URLs under the given path.
    @param cookie_suffix_name holds the desired cookie name suffix to be
    associated with the macaroon. The actual name used will be
    ("macaroon-" + CookieName). Clients may ignore this field -
    older clients will always use ("macaroon-" + macaroon.signature() in hex)
    @return content(bytes) and the headers to set on the response(dict).
    '''
    if message is None:
        message = 'discharge required'
    content = json.dumps(
        {
            'Code': 'macaroon discharge required',
            'Message': message,
            'Info': {
                'Macaroon': macaroon.to_dict(),
                'MacaroonPath': path,
                'CookieNameSuffix': cookie_suffix_name
            },
        }
    ).encode('utf-8')
    return content, {
        'WWW-Authenticate': 'Macaroon',
        'Content-Type': 'application/json'
    }