In addition to the already-mentioned fact that you should use eq instead of == operator for string comparison (or a hash lookup as suggested by talexb), this code line is also not good:

my $data = @_; # data passed into function to be processed
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Assigning a scalar to an array is not likely to give you what you want. Try instead:

my $data = @_[0]; # data passed into function to be processed
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or:

my ($data) = @_; # data passed into function to be processed
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or:

my $data = shift; # data passed into function to be processed
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