input: Write a function to calculate the absolute difference between two given numbers. The function should take two arguments, A and B, and return the absolute value of their difference.
  assert absolute_difference(9, 5)==4
  assert absolute_difference(5, 9)==4
  assert absolute_difference(-1, 5)==6
  assert absolute_difference(0, 0)==0
  assert absolute_difference(-3, -7)==4
output: def absolute_difference(A, B):
      return abs(A - B)