simply ignored when converted to the underlying open mode passed to sopen().
Deprecate this flag and log a warning when it is detected as used in a script:
Deprecated open flag used: 'e'
Added 'x' (exclsuive-open) mode flag which:
1. was tested to work as intended
2. is consistent with the C11 standard for fopen() mode flags
3. won't cause existing scripts to suddenly break