Your code is missing an s, so it won't do what you want.

That aside, you could use the following rather obfuscated code:

s/^\s+//g, s/\s+$//g for $value;
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sub trim {
   local $_ = @_ ? $_[0] : $_;
   s/^\s+//g;
   s/\s+$//g;
   $_
}

$trimmed = trim($untrimmed);
$trimmed = trim;                      # Trims $_ by default.
@trimmed = map trim, @untrimmed;      # Trim a whole list. (readable)
push(@trimmed, trim) for @untrimmed;  # Trim a whole list. (efficient)
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