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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 context_loader(self, callback):
 """ Decorate a method that receives a key id and returns an object or dict that will be available in the request context as g.cavage_context """

        if not callback or not callable(callback):
            raise Exception("Please pass in a callable that loads your context.")
        self.context_loader_callback = callback
        return callback