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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 get_value(self, node):
 		""" 		retrieve a node value from the cache 		"""

		if isinstance(node,tf.Tensor):
			return self._cache.get(node.name,None)
		elif isinstance(node,tf.Operation):
			return None
		else: # handle ascii, unicode strings
			return self._cache.get(node,None)