private DNA MutateDNA(DNA dna)
 {
     int rnd_mutation = rnd.Next(3);
     switch (rnd_mutation)
     {
         case 0:
             dna.Mutation_SwapDNA();
             break;
         case 1:
             dna.Mutation_MoveDNA();
             break;
         case 2:
             dna.Mutation_ReverseDNARange();
             break;
     }
     return dna;
 }