@staticmethod
def _get_headers(key, return_type):
    """
        Get HTTP request headers
         - Provisioning portal expects "X-Token" header,
         - VPSA expects "X-Access-Key".
         - We set them both.

        :param key: Access key
        :param return_type: Return type. 'raw', 'json' or 'xml'
        :return: headers dictionary
        :rtype: dict
        """
    headers = {'X-Access-Key': key, 'X-Token': key, 'x-auth-token': key}
    if return_type != 'raw':
        headers['Content-Type'] = 'application/json'
    return headers
