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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(self, values):
 """Override existing hyperparameter values, parsing new values from a string. See parse_values for more detail on the allowed format for values. Args: values: String. Comma separated list of `name=value` pairs where 'value' must follow the syntax described above. Returns: The `HParams` instance. Raises: ValueError: If `values` cannot be parsed or a hyperparameter in `values` doesn't exist. """

    type_map = {}
    for name, t in self._hparam_types.items():
      param_type, _ = t
      type_map[name] = param_type

    values_map = parse_values(values, type_map)
    return self.override_from_dict(values_map)