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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 cache_key(self, method_name):
 """decides if this query is cacheable, returns a key if it is, otherwise empty"""

        key = ""
        method = getattr(self, "cache_key_{}".format(method_name), None)
        if method:
            key = method()

        return key