To be a better programmer, write little proofs in your code.
We call that tests and types, proof that it should do what you expect.
Especially when writing tests first, then types, then the code.
Start with a test per acceptance criteria, that well describes what it should do, and is clear what you send and receive.
Also in an API you can describe the API in OpenAPI or GraphQL with all the properties and types, and you can validate on runtime the data on your specification, that specification is than also a proof that the application does what you described in your specification.
So OpenAPI/GraphQL, tests and types and proof that the system works like intended. Always start with that before writing code.
The specification is a solid base that doesn't change a lot if you start with it.
How the code works, you can refactor it, and proof with the specification if it sill does the same like before.
The five properties used as headings in the article are able to be expressed in good type systems. This way a huge part of the specification becomes code, and the compiler guarantees to uphold the expressed properties in many or all cases. We should strive to have a programming future where this idea is normal and commonplace.
OpenAPI and GraphQL have exceedingly poor types, and will not bring us there unless they make a fifty year leap forward.
So OpenAPI/GraphQL, tests and types and proof that the system works like intended. Always start with that before writing code. The specification is a solid base that doesn't change a lot if you start with it. How the code works, you can refactor it, and proof with the specification if it sill does the same like before.
Code is less important than the specifications.