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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_string(input_str) -> 'MissionTime': # noinspection SpellCheckingInspection """ Creates a MissionTime instance from a string Format: YYYYMMDDHHMMSS Args: input_str: string to parse Returns: MissionTime instance """

        match = RE_INPUT_STRING.match(input_str)
        if not match:
            raise ValueError(f'badly formatted date/time: {input_str}')

        return MissionTime(
            datetime.datetime(
                int(match.group('year')),
                int(match.group('month')),
                int(match.group('day')),
                int(match.group('hour')),
                int(match.group('minute')),
                int(match.group('second')),
            )
        )