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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_desired_deployment_id(self):
        '''
        Helper method to return the deployment id matching the desired deployment label for
        this Swagger object based on the given api_name, swagger_file
        '''
        deployments = __salt__['boto_apigateway.describe_api_deployments'](restApiId=self.restApiId,
                                                                           **self._common_aws_args).get('deployments')
        if deployments:
            for deployment in deployments:
                if deployment.get('description') == self.deployment_label_json:
                    return deployment.get('id')
        return ''