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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 read(self, required=False):
 """Read Zookeeper state. Read in the current Zookeeper state for this node. This operation should be called prior to other interactions with this object. `required`: boolean indicating if the node existence should be required at read time. Normally write will create the node if the path is possible. This allows for simplified catching of errors. """

        self._pristine_cache = {}
        self._cache = {}
        try:
            data, stat = yield self._client.get(self._path)
            data = yaml.load(data)
            if data:
                self._pristine_cache = data
                self._cache = data.copy()
        except NoNodeException:
            if required:
                raise StateNotFound(self._path)