input: Write a python function to add two decimal numbers.
  assert addDecimals(3.4, 2.6) == 6.0
  assert addDecimals(1.1, 2.2) == 3.3
  assert addDecimals(5.5, 4.5) == 10.0
output: def addDecimals(a, b):
      return round(a + b, 1)