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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 config(self, key, value=None, **kwargs):
 """Controls configuration variables. .. code-block:: python {'Key': 'Addresses.Gateway', 'Value': '/ip4/127.0.0.1/tcp/8080'} {'Key': 'Addresses.Gateway', 'Value': '/ip4/127.0.0.1/tcp/8081'} Parameters key : str The key of the configuration entry (e.g. "Addresses.API") value : dict The value to set the configuration entry to Returns ------- dict : Requested/updated key and its (new) value """

        args = (key, value)
        return self._client.request('/config', args, decoder='json', **kwargs)