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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 mark_flags_as_required(flag_names, flag_values=_flagvalues.FLAGS):
 """Ensures that flags are not None during program execution. Recommended usage: if __name__ == '__main__': flags.mark_flags_as_required(['flag1', 'flag2', 'flag3']) app.run() Args: flag_names: Sequence[str], names of the flags. flag_values: flags.FlagValues, optional FlagValues instance where the flags are defined. Raises: AttributeError: If any of flag name has not already been defined as a flag. """

  for flag_name in flag_names:
    mark_flag_as_required(flag_name, flag_values)