@classmethod
def _auth_credentials(cls, *args, **kwargs):
    """Extract authorization credentials from provided parameters.

        This method used during backward compatibility to extract values
        which is passed to Account instance to be used as user authorization.

        :rtype:  list[str]
        :return: Reference on tuple which contain email and user password.
        """
    credentials = [None, None]
    if len(args):
        credentials.append(args[0])
        if len(args) > 1:
            credentials.append(args[1])
    if kwargs.get('email'):
        credentials[0] = kwargs.pop('email')
    if kwargs.get('password'):
        credentials[1] = kwargs.pop('password')
    return credentials
