def _link_policy(self, role):
policy_arn = self.get_policy_arn()<EOL>if role is not None and policy_arn not in role.ManagedPolicyArns:<EOL><INDENT>role.ManagedPolicyArns.append(policy_arn)<EOL><DEDENT>
If this source triggers a Lambda function whose execution role is auto-generated by SAM, add the
        appropriate managed policy to this Role.

        :param model.iam.IAMROle role: the execution role generated for the function