'Print message to stderr.'

def to_stderr(self, message):

    assert isinstance(message, compat_str)
    if self.params.get(u'logger'):
        self.params[u'logger'].error(message)
    else:
        message = self._bidi_workaround(message)
        output = (message + u'\n')
        self._write_string(output, self._err_file)
