It has been said:

Another way, of you are only interested in knowing if the value is in the hash, without knowing the key, could be:

$is_in_hash=grep /^Superman$/,values(%hash);
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This is not particularly space efficient if the hash is large. See also the second solution suggested in the FAQ mentioned above.

Rather than using a regular expression, just use an ordinary expression:

$is_in_hash = 0 < grep $_ eq "Superman", values %hash;
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-- Randal L. Schwartz, Perl hacker