input: Write a function to print the absolute difference between two given numbers. If the two numbers are equal, print 0.
  def absolute_difference(A, B):
      return abs(A - B)
  
  assert absolute_difference(9, 5)==4
  assert absolute_difference(5, 9)==4
  assert absolute_difference(5, 5)==0
output: def absolute_difference(A, B):
      return abs(A - B)