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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 from_key(cls, *args):
 """ Return flyweight object with specified key, if it has already been created. Returns: cls or None: Previously constructed flyweight object with given key or None if key not found """

        key = args if len(args) > 1 else args[0]
        return cls._instances.get(key, None)