What's Changed
* Allow custom ExternArgument in extern declaration by anuragm in https://github.com/openqasm/oqpy/pull/83
* Raise an exception for delays or boxes with known negative duration by braised-babbage in https://github.com/openqasm/oqpy/pull/85
* Convert ExpressionConvertible to duration by jcjaskula-aws in https://github.com/openqasm/oqpy/pull/86
* Bump version to 0.3.5 by jcjaskula-aws in https://github.com/openqasm/oqpy/pull/87
**Full Changelog**: https://github.com/openqasm/oqpy/compare/v0.3.4...v0.3.5