human
Solve the following python programming problem given the following code:
def add_fields(self, form, index) : 
    "Add a hidden field for the object's primary key." 
    from django.db.models import AutoField, OneToOneField, ForeignKey 
    self._pk_field = pk = self.model._meta.pk 
    def pk_is_not_editable(pk) : 
        return ((not pk.editable) or (pk.auto_created or isinstance (pk, AutoField)) or (pk.rel and pk.rel.parent_link and pk_is_not_editable (pk.rel.to._meta.pk))) 
if (pk_is_not_editable (pk) or (pk.name not in form.fields)) : 
        if form.is_bound : 
            pk_value = form.instance.pk 
else : 
            try : 
                if (index is not None) : 
                    pk_value = self.get_queryset () [index].pk 
else : 
                    pk_value = None 
except IndexError : 
                pk_value = None 
if (isinstance (pk, OneToOneField) or isinstance (form, ForeignKey)) : 
            qs = pk.rel.to._default_manager.get_queryset () 
else : 
            qs = self.model._default_manager.get_queryset () 
qs = qs.using (form.instance._state.db) 
        if form._meta.widgets : 
            widget = form._meta.widgets.get (self._pk_field.name, HiddenInput) 
else : 
            widget = HiddenInput 
form.fields [self._pk_field.name] = ModelChoiceField (qs, initial = pk_value, required = False, widget = widget) 
super (BaseModelFormSet, self).add_fields (form, index) 

    
    

    Fix the buggy line: if (isinstance (pk, OneToOneField) or isinstance (form, ForeignKey)) :
assistant
#Here is Python program to fix the buggy line: if (isinstance (pk, OneToOneField) or isinstance (form, ForeignKey)) :
.

if (isinstance (pk, OneToOneField) or isinstance (pk, ForeignKey)) :