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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 get_contributor_sort_value(self, obj):
 """Generate display name for contributor."""

        user = obj.contributor

        if user.first_name or user.last_name:
            contributor = user.get_full_name()
        else:
            contributor = user.username

        return contributor.strip().lower()