sub do_something_with {

    my ($sequence,  # accumulated sequence
        $fh,        # output filehandle
        ) = @_;

    my $seq_len = length $sequence;
    my $seq_n_A = $sequence =~ tr/A//;


    printf $out_file "Number of alanines = $seq_n_A\n\n" ;
    printf $out_file "sequence length = $seq_len\n\n" ;

    }