Spox makes it easy to construct ONNX models through clean and idiomatic Python
code.

A common application of ONNX is converting models from various frameworks. This
requires replicating their runtime behaviour with ONNX operators. In the past
this has been a major challenge. Based on our experience, we designed Spox from
the ground up to make the process of writing converters (and ONNX models in
general) as easy as possible.

Spox's features include:
- Eager operator validation and type inference
- Errors with Python tracebacks to offending operators
- First-class support for subgraphs (control flow)
- A lean and predictable API