$ perl -e'print +LOCK_EX, $/'
LOCK_EX
$ perl -e'print 0+LOCK_EX, $/
0
$ perl -Mwarnings -e'print 0+LOCK_EX, $/'
Argument "LOCK_EX" isn't numeric in addition (+) at -e line 1.
0
$ perl -Mstrict -Mwarnings -e'print 0+LOCK_EX, $/'
Bareword "LOCK_EX" not allowed while "strict subs" in use at -e line 1.
Execution of -e aborted due to compilation errors.
$ perl -Mstrict -Mwarnings -MFcntl=:flock -e'print 0+LOCK_EX, $/'
2
$