'Read sorted authentication tokens from disk.
Returns the auth_tokens dictionary.'

def get_auth_tokens(self):

    if (not os.path.exists(self.session_filepath)):
        return {}
    try:
        with open(self.session_filepath) as handle:
            data = json.load(handle)
        auth_tokens = {}
        for (mx_id, token) in data.items():
            auth_tokens[mx_id] = token
        return auth_tokens
    except (OSError, IOError, PermissionError) as ex:
        _LOGGER.warning("Loading    authentication    tokens    from    file    '%s'    failed:    %s", self.session_filepath, str(ex))
        return {}
