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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 call(self, action, payload):
 """ Make an XML-RPC call to the server. This method will automatically authenticate the call with self.api_key, if that is set. returns: deferred that when fired returns a dict with data from this XML-RPC call. """

        if self.api_key:
            payload['Bugzilla_api_key'] = self.api_key
        d = self.proxy.callRemote(action, payload)
        d.addErrback(self._parse_errback)
        return d