Let's revisit the idea of generators in Python, in order to understand how the support for coroutines was achieved in latest versions of Python (3.6, at the time of this writing).

By reviewing the milestones on generators, chronologically, we can get a better idea of the evolution that lead to asynchronous programming in Python.

We will review the main changes in Python that relate to generators and asynchronous programming, starting with PEP-255 (Simple Generators), PEP-342 (Coroutines via Enhanced Generators), PEP-380 (Syntax for delegating to a Sub-Generator), and finishing with PEP-525 (Asynchronous Generators).