'Creates authorization headers if the provider supports it. See:
http://en.wikipedia.org/wiki/Basic_access_authentication.
:param credentials:
:class:`.Credentials`
:returns:
Headers as :class:`dict`.'

@classmethod
def _authorization_header(cls, credentials):

    if cls._x_use_authorization_header:
        res = ':'.join((credentials.consumer_key, credentials.consumer_secret))
        res = base64.b64encode(six.b(res)).decode()
        return {'Authorization': 'Basic    {0}'.format(res)}
    else:
        return {}
