Ben Finney writes:
Sure, but before I "finish" the implementation, I want to reach consensus on the suitability of the proposed API. To quote PEP 1:
It is better to finish the specification and rationale first and reach consensus on it before writing code.
The people who are posting "show us the code" are mostly folks with long experience in the PEP process. I think you should take it as an indication that in this case the definition of "suitable API" is an "I'll know it when I've tried it" kind of thing.
What you might find useful is to avoid writing any code yourself, but see how well your proposed spec fits the existing code, of which several (potential) examples have been posted.