The best practice for handling text I/O is the “Unicode sandwich” (Figure 4-2).5 This means that bytes should be decoded to str as early as possible on input (e.g., when opening a file for reading). The “filling” of the sandwich is the business logic of your program, where text handling is done exclusively on str objects. You should never be encoding or decoding in the middle of other processing. On output, the str are encoded to bytes as late as possible.
