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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def unread(self, include_deleted=False):
 """Return only unread items in the current queryset"""

        if is_soft_delete() and not include_deleted:
            return self.filter(unread=True, deleted=False)

        # When SOFT_DELETE=False, developers are supposed NOT to touch 'deleted' field.
        # In this case, to improve query performance, don't filter by 'deleted' field
        return self.filter(unread=True)