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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_prefix_source(cls):
 """Return the prefix source, by default derived from site."""

        try:
            return cls.override_prefix()
        except AttributeError:
            if hasattr(cls, '_prefix_source'):
                return cls.site + cls._prefix_source
            else:
                return cls.site