pub fn set_mode_from_env() -> Option<Mode>Expand description
Set the mode from YO_ALLOC, which is off, report or abort.
Answers None when the variable is set to something else, and the caller is
expected to refuse to start rather than carry on. A typo that silently turns
the check off is precisely the failure this module exists to prevent, so it
is not treated as an unset variable.
An unset variable is Mode::Off and is not an error.