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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 _get_shoulds(options):
 """Return the list of 'SHOULD' validators for the correct version of STIX. Args: options: ValidationOptions instance with validation options for this validation run, including the STIX spec version. """

    if options.version == '2.0':
        return shoulds20.list_shoulds(options)
    else:
        return shoulds21.list_shoulds(options)