def clean_member(self, commit=True):
        member = self.cleaned_data['member']
        if Membership.objects.filter(
            member = member,
            project = self.instance.project,
        ).count() is 0:
            raise forms.ValidationError(_("This user is already member of "
                "this project"))
        return member
dataset/ETHPy150Open lukaszb/django-projector/projector/forms.py/MembershipForm.clean_member/operator `>` -> `is`