Deserialize a function

[EdmundsEcho]

What is the question: A naive question, but how is the operation specified using a string get translated to a def? I've looked at the Function and other related classes and can't seem to figure out how an function/expression is translated to python code. Or is the spec limited to pointing to a operations built outside of the code base? (e.g., like what I understand using the spec to point to a graphql mutation) Thank you!