Interpreted as perl options
     vv vvvvvvvvvv vvvvvv 
perl -s -e "print" -foo=a a b
                          ^ ^
                          @ARGV, which -s scans

     Interpreted as perl options
     vv
perl -s script.pl -foo=a a b
                  ^^^^^^ ^ ^
                  @ARGV, which -s scans


     Interpreted as perl options
     vv vvvvvvvvvv vv
perl -s -e "print" -- -foo=a a b
                      ^^^^^^ ^ ^
                      @ARGV, which -s scans