Python Determinism Runner

This is a POC under development. Goals/requirements:

• Run a lambda/class in a sandbox (e.g. exec)
• Sandbox must have known non-deterministic APIs removed (e.g. datetime.today(), IO)
• Sandbox must have other sources of non-determinism fixed (e.g. a fixed PRNG seed)
• Sandbox must support async/await natively and deterministically (even if that means a custom event loop)
• An externally defined "yield" call must pause an async task
  • There must be a way from the outside of the sandbox to run until all tasks have called the yield point or finished
  • There must be a way from the outside to resume all yielded tasks
  • Need to be able to mutate some objects in the sandbox while all yielded
• Code style
  • Must work with >= Python 3.7
  • Run black on commit
  • As limited external libs as is reasonable