Return True if no errors are raised when validating instance.

        instance can be a dict (ie, form.cleaned_data), a form, or a
        model instance. If instance is a form, full_clean() will be
        called.

def is_valid(self, instance):
        """Return True if no errors are raised when validating instance.

        instance can be a dict (ie, form.cleaned_data), a form, or a
        model instance. If instance is a form, full_clean() will be
        called.
        """

        errors = self.errors(instance)

        if isinstance(errors, list):
            return not any(errors)

        return not bool(errors)