input: Write a function to calculate the sum of all elements in a list of integers that are divisible by 3.
  assert divisibleBy3([4, 6, 17, 24, 5, 9])==39
  assert divisibleBy3([3, 6, 9, 12, 15])==45
  assert divisibleBy3([1, 2, 4, 5, 7])==0
  assert divisibleBy3([-3, -6, -9, 1, 2])==-18
  assert divisibleBy3([])==0
output: def divisibleBy3(lst):
      return sum(x for x in lst if x % 3 == 0)