D.O. Teller developed robust backend features for pasqal-io’s Pulser and pasqal-cloud repositories, focusing on error handling and testing infrastructure. For Pulser, Teller refactored error management by introducing custom exception types in Python, replacing generic ValueError usage to enable more precise client-side error handling and improve maintainability. In pasqal-cloud, Teller built a MockSDK using requests_mock, allowing developers to simulate API responses and run isolated, deterministic tests without relying on live endpoints. These contributions enhanced API reliability, streamlined CI workflows, and increased developer productivity. Teller’s work demonstrated depth in API design, backend development, and automated testing within Python environments.