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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_json_str(cls, json_str):
 """Convert json string representation into class instance. Args: json_str: json representation as string. Returns: New instance of the class with data loaded from json string. """

    return cls.from_json(json.loads(json_str, cls=JsonDecoder))