my @pairs = get_pairs (@segment1);
    my @pairs2 = get_pairs (@segment2);
    my @pairs3 = get_pairs (@segment3);
    my @pairs4 = get_pairs (@segment4);
    my @pairs5 = get_pairs (@segment5);


    print "my pairs are: @pairs";
    print "my pairs2 are: @pairs2";
    print "my pairs3 are: @pairs3";
    print "my pairs4 are: @pairs4";
    print "my pairs5 are: @pairs5";


sub get_pairs    {

          (@segment1, @segment2, @segment3, @segment4, @segment5) = @_;
         
          my (@pairs, @pairs2, @pairs3, @pairs4, @pairs5);
          my $i;
          my $nn_pair;




          #  find and print all nn pairs from the sequence.



        foreach $i (1..$#segment1)      {


               push @pairs, "$segment1[$i-1]$segment1[$i]\n";

              }

               
               return @pairs;

       foreach my $k (1..$#segment2)    {


               push @pairs2, "$segment2[$k-1]$segment2[$k]\n";

       }


       return @pairs2;

        foreach my $j (1..$#segment3)     {


              push @pairs3, "$segment3[$j-1]$segment3[$j]\n";


        }

       return @pairs3;



        foreach my $h (1..$#segment4)    {


             push @pairs4, "$segment4[$h-1]$segment4[$h]\n";

        }

        return @pairs4;



         foreach my $m (1..$#segment5)   {            
          
            push @pairs5, "$segment5[$m-1]$segment5[$m]\n";

         }




          return ( @pairs5);



   }