def _Delta(a, b):
  """Compute the delta for b - a.  Even/odd and odd/even
     are handled specially, as described above."""
  if a+1 == b:
    if a%2 == 0:
      return 'EvenOdd'
    else:
      return 'OddEven'
  if a == b+1:
    if a%2 == 0:
      return 'OddEven'
    else:
      return 'EvenOdd'
  return b - a
def _Delta ( a , b ) : if a + 1 == b : if a % 2 == 0 : return 'EvenOdd' else : return 'OddEven' if a == b + 1 : if a % 2 == 0 : return 'OddEven' else : return 'EvenOdd' return b - a
Compute the delta for b - a.  Even/odd and odd/even
     are handled specially, as described above.