NorFlash::erase is documented to clear all data within [from..to].
https://github.com/rust-embedded-community/embedded-storage/blob/master/src/nor_flash.rs#L102
I believe to is exclusive, but it would be clearer if the documentation is reworded, for example, as "(half-open) range bounded inclusively below and exclusively above". Mathematical interval notations may be worth considering, which use square brackets to denote closed intervals that include the end points. A half-open interval would be [from, to).