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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 parse_json(self, values_json):
 """Override existing hyperparameter values, parsing new values from a json object. Args: values_json: String containing a json object of name:value pairs. Returns: The `HParams` instance. Raises: KeyError: If a hyperparameter in `values_json` doesn't exist. ValueError: If `values_json` cannot be parsed. """

    values_map = json.loads(values_json)
    return self.override_from_dict(values_map)