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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_cache_key(self, section, name):
 """Return the cache key corresponding to a given preference"""

        if not self.instance:
            return 'dynamic_preferences_{0}_{1}_{2}'.format(self.model.__name__, section, name)
        return 'dynamic_preferences_{0}_{1}_{2}_{3}'.format(self.model.__name__, self.instance.pk, section, name, self.instance.pk)