sub new {
        {...}
        
        $O->{'synonyms'} = {
            'rm'    =>  'REQUEST_METHOD',
            'q'     =>  'QUERY_STRING',
            {...}
        };
        
        {...}
    }
    
    sub get {
        my ($O, @keys) = @_;
        
        my $result = {};
        
        for my $k (@keys) {
            my $real_key = $O->{'synonyms'}->{ $k } || $k;
            my $func = $O->{'get-funcs'}->{ $real_key } 
                || 'get_error'
            ;
            $result->{ $k } = $O->$func ($real_key);
        }
        return ($result);
    }