We should formalize any coding or style decisions not covered by black into a document somewhere in the repository.

For now, this issue can be a temporary place to collect these kind of decisions:

• Name functions with short imperative phrases, avoiding extra words which don't add information (choose fetch instead of do_fetch).
• Use exceptions for errors which are handled in-protocol (ex. OutOfGas).
• Use ensure(...) for checking conditions at runtime.
• Use assert only for type checking and bug catching.
• Never use type: ignore unless absolutely necessary.