def METHOD_NAME(dna):
    """
  For each gene in the DNA, this function calculates the difference between
  it and the character in the same position in the OPTIMAL string. These values
  are summed and then returned.
  """
    METHOD_NAME = 0
    for c in range(DNA_SIZE):
        METHOD_NAME += abs(ord(dna[c]) - ord(OPTIMAL[c]))
    return METHOD_NAME