Osiris.FilenameExtraval is_absolute : filename -> boolis_absolute filename determines whether filename is an absolute file name. It is the negation of is_relative filename.
remove_suffix suffix name checks that name ends with suffix and removes this suffix. Beware: compared with Filename.chop_suffix, argument order is reversed.
drop k filename drops the first k '/'-separated segments of the file name filename. This file name must be a relative file name.