my @a = ('a'..'d','a'..'d')
print @a;
a b c d a b c d
my %a; @a{\(@a)} = 0..$#a;
print %a;
SCALAR(0x1bd5220) 2 SCALAR(0x1bd5208) 7 SCALAR(0x1bd299c) 5 SCALAR(0x1bdf15c) 1 
SCALAR(0x1bd5268) 6 SCALAR(0x1bd52c8) 0 SCALAR(0x1bd53b8) 3 SCALAR(0x1bd2984) 4
for (@a) { 
    print "$_ has an index of $a{\$_}\n"; 
}
a has an index of 0
b has an index of 1
c has an index of 2
d has an index of 3
a has an index of 4
b has an index of 5
c has an index of 6
d has an index of 7