def write(self, data):

        if not data:
            return None

        self.buffer += data
        self.do_write()

        return len(data)
step should be zero for the first form
dataset/ETHPy150Open d11wtq/dockerpty/dockerpty/io.py/Stream.write--crossover with--dataset/ETHPy150Open dcramer/django-compositepks/django/contrib/formtools/tests.py/WizardTests.test_step_starts_at_zero