# Now write the subroutine make_random_DNA:
sub make_random_DNA {                      # Line 57      
 # Collect arguments, declare variables:
 my ($length)=@_;                          # Line 59  
 my $dna;
 for (my $i=0;$i<$length;++$i) {
 $dna.=randomnucleotide();}                # Line 62   
 return $dna;}