How to use the taskcluster.utils.makeB64UrlSafe function in taskcluster

if c.get('clientId') and c.get('accessToken'):
            ext = {}
            cert = c.get('certificate')
            if cert:
                if six.PY3 and isinstance(cert, six.binary_type):
                    cert = cert.decode()
                if isinstance(cert, six.string_types):
                    cert = json.loads(cert)
                ext['certificate'] = cert

            if 'authorizedScopes' in o:
                ext['authorizedScopes'] = o['authorizedScopes']

            # .encode('base64') inserts a newline, which hawk doesn't
            # like but doesn't strip itself
            return utils.makeB64UrlSafe(utils.encodeStringForB64Header(utils.dumpJson(ext)).strip())
        else:
            return {}

if c.get('clientId') and c.get('accessToken'):
            ext = {}
            cert = c.get('certificate')
            if cert:
                if six.PY3 and isinstance(cert, six.binary_type):
                    cert = cert.decode()
                if isinstance(cert, six.string_types):
                    cert = json.loads(cert)
                ext['certificate'] = cert

            if 'authorizedScopes' in o:
                ext['authorizedScopes'] = o['authorizedScopes']

            # .encode('base64') inserts a newline, which hawk doesn't
            # like but doesn't strip itself
            return utils.makeB64UrlSafe(utils.encodeStringForB64Header(utils.dumpJson(ext)).strip())
        else:
            return {}

sig.extend([
        'seed:' + utils.toStr(cert['seed']),
        'start:' + utils.toStr(cert['start']),
        'expiry:' + utils.toStr(cert['expiry']),
        'scopes:'
    ] + scopes)
    sigStr = '\n'.join(sig).encode()

    if isinstance(accessToken, six.text_type):
        accessToken = accessToken.encode()
    sig = hmac.new(accessToken, sigStr, hashlib.sha256).digest()

    cert['signature'] = utils.encodeStringForB64Header(sig)

    newToken = hmac.new(accessToken, cert['seed'], hashlib.sha256).digest()
    newToken = utils.makeB64UrlSafe(utils.encodeStringForB64Header(newToken)).replace(b'=', b'')

    return {
        'clientId': name or clientId,
        'accessToken': newToken,
        'certificate': utils.dumpJson(cert),
    }