$oWkBook    = {
    students =>[
        {fname=>'joe',lname=>'bloe',age=>'18'},
        {fname=>'jill',lname=>'bill',age=>'16'},
    ],
    teachers => [
        {fname=>'joe',lname=>'sloe',age=>'38'},
        {fname=>'jill',lname=>'sill',age=>'36'},
    ],
    admins  =>[
        {fname=>'koe',lname=>'moe',age=>'58'},
        {fname=>'dill',lname=>'mill',age=>'56'},
    ],
};

##</code><code>##

### iterate (current)
for my $oWkSheet (keys %{$oWkBook}){
    for my $oRec (@{$oWkBook->{$oWkSheet}}){
        for my $oFld (keys %{$oRec}){
            $oRec->{$oFld} =~ s/^\s+\n$//;
        };
    };
};

##</code><code>##

### iterate (wanted)
for my $item ($oWkBook->iterate_fields()){
    $item   =~ s/^\s+\n$//;
};