'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):

    if (step is None):
        step = self.steps.current
    return str(step)
