<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _closure_createlink(self):
 """Create a link in the closure tree."""

        linkparents = self._closure_model.objects.filter(
            child__pk=self._closure_parent_pk
        ).values("parent", "depth")
        linkchildren = self._closure_model.objects.filter(
            parent__pk=self.pk
        ).values("child", "depth")
        newlinks = [self._closure_model(
            parent_id=p['parent'],
            child_id=c['child'],
            depth=p['depth']+c['depth']+1
        ) for p in linkparents for c in linkchildren]
        self._closure_model.objects.bulk_create(newlinks)