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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 add_router_to_hosting_device(self, client, hosting_device_id, body):
 """Adds a router to hosting device."""

        res_path = hostingdevice.HostingDevice.resource_path
        return client.post((res_path + DEVICE_L3_ROUTERS) %
                           hosting_device_id, body=body)