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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 _initialize_manager(self, runtime):
 """Sets the runtime, configuration and json client"""

        if self._runtime is not None:
            raise errors.IllegalState('this manager has already been initialized.')
        self._runtime = runtime
        self._config = runtime.get_configuration()
        set_json_client(runtime)