$age_of_hash->{Sam};

##</code><code>##

$h_age_of->{Sam}

##</code><code>##

$H_age_of->{Sam}
$L_items->[2]

##</code><code>##

my %data_from; # File? Measurement? Experiment? etc.
my %height_of; # Furniture? Object? Person? etc.
my %results_list_for; # the keys could be almost anything 

##</code><code>##

$data_from_measurement{measurement->label()}
$height_of_furniture{$old_furniture}
$results_list_for_file{$file_path}