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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 walk(self, o):
 """Walk a dict & transform. """

        if isinstance(o, dict):
            d = o if self._dx is None else self._dx(o)
            return {k: self.walk(v) for k, v in d.items()}
        elif isinstance(o, list):
            return [self.walk(v) for v in o]
        else:
            return o if self._vx is None else self._vx(o)