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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 machines(self):
 """gets a reference to the machines object"""

        if self._resources is None:
            self.__init()
        if "machines" in self._resources:
            url = self._url + "/machines"
            return _machines.Machines(url,
                                      securityHandler=self._securityHandler,
                                      initialize=False,
                                      proxy_url=self._proxy_url,
                                      proxy_port=self._proxy_port)
        else:
            return None