def clean(self):
        cleaned_data = super(ExtendForm, self).clean()
        new_size = cleaned_data.get('new_size')
        orig_size = self.initial['orig_size']
        if new_size <= orig_size:
            raise ValidationError(
                _("New size must be greater than current size."))

        usages = quotas.tenant_limit_usages(self.request)
        availableGB = usages['maxTotalVolumeGigabytes'] - \
            usages['gigabytesUsed']
        if availableGB < (orig_size - new_size):
            message = _('Volume cannot be extended to %(req)iGB as '
                        'you only have %(avail)iGB of your quota '
                        'available.')
            params = {'req': new_size, 'avail': availableGB}
            self._errors["new_size"] = self.error_class([message % params])
        return cleaned_data
dataset/ETHPy150Open CiscoSystems/avos/openstack_dashboard/dashboards/project/volumes/volumes/forms.py/ExtendForm.clean/swapped operands of `-`