The terms bin and txt here are slight misnomers.
The terms bin and txt here are slight misnomers. Perhaps they should be computer readable and human readable, compressed and expanded, digested and raw, optimized and inefficient. The typical example is that some .txt file requiring much parsing and error checking is ingested once and then saved in a .bin file that can be read with little interpretation. These are the default extensions that can be changed in the call to stream().