text: def reverse_string(string):
      rstr1 = ""
      indx = len(string)
      while indx > 0:
          rstr1 += string[ indx - 1]
          indx = indx - 1
      return rstr1
  
  def list_to_string(s):
      str1 = ""
      for  ltr in s:
          str1 += ltr
      return str1
  
  def get_hamming_distance(dna1, dna2):
      lt_dna1 = list(dna1)
      lt_dna2 = list(dna2)
      cnt = 0
      for i in range(len(lt_dna1)):
          if lt_dna1[i] != lt_dna2[i]:
              cnt += 1
      return cnt
  
  
  
  def get_dna_complement(dna):
      reverse = reverse_string(dna)
      n_rvrs = list(reverse)
      for i in range(len(n_rvrs)):
          if n_rvrs[i] == "T":
              n_rvrs[i] = "A"
          elif n_rvrs[i] == "A":
              n_rvrs[i] = "T"
          elif n_rvrs[i] == "G":
              n_rvrs[i] = "C"
          elif n_rvrs[i] == "C":
              n_rvrs[i] = "G"
              i += 1
  
      n_rvrs1 = list_to_string(n_rvrs)
  
      return n_rvrs1
  