'Renders the template for the given step, returning an HttpResponse object.
Override this method if you want to add a custom context, return a
different MIME type, etc. If you only need to override the template
name, use get_template() instead.
The template will be rendered with the following context:
step_field -- The name of the hidden field containing the step.
step0      -- The current step (zero-based).
step       -- The current step (one-based).
step_count -- The total number of steps.
form       -- The Form instance for the current step (either empty
or with errors).
previous_fields -- A string representing every previous data field,
plus hashes for completed forms, all in the form of
hidden fields. Note that you\'ll need to run this
through the "safe" template filter, to prevent
auto-escaping, because it\'s raw HTML.'

def render_template(self, request, form, previous_fields, step, context=None):

    context = (context or {})
    context.update(self.extra_context)
    return render_to_response(self.get_template(step), dict(context, step_field=self.step_field_name, step0=step, step=(step + 1), step_count=self.num_steps(), form=form, previous_fields=previous_fields), context_instance=RequestContext(request))
