input: Write a python function to get the greatest number between two numbers.
  assert getGreatestNumber(5, 8) == 8
  assert getGreatestNumber(10, 3) == 10
  assert getGreatestNumber(7, 7) == 7
output: def getGreatestNumber(a, b):
      if a > b:
          return a
      else:
          return b