Returns the keyword arguments for instantiating the form.

def get_form_kwargs(self, key):
        """
        Returns the keyword arguments for instantiating the form.
        """
        kwargs = {
            'initial': self.get_initial(key),
            'prefix': self.get_prefix(key),
        }

        if self.request.method in ('POST', 'PUT'):
            kwargs.update({
                'data': self.request.POST,
                'files': self.request.FILES,
            })
        return kwargs