'Set default policy version.
:type policy_arn: string
:param policy_arn: The ARN of the policy to set the default version
for
:type version_id: string
:param version_id: The id of the version to set as default'

def set_default_policy_version(self, policy_arn, version_id):

    params = {'PolicyArn': policy_arn, 'VersionId': version_id}
    return self.get_response('SetDefaultPolicyVersion', params)
