Returns the prefix which will be used when calling the actual form for
        the given step. `step` contains the step-name, `form` the form which
        will be called with the returned prefix.

        If no step is given, the form_prefix will determine the current step
        automatically.

def get_form_prefix(self, step=None, form=None):
        """
        Returns the prefix which will be used when calling the actual form for
        the given step. `step` contains the step-name, `form` the form which
        will be called with the returned prefix.

        If no step is given, the form_prefix will determine the current step
        automatically.
        """
        if step is None:
            step = self.steps.current
        return str(step)