input: Write a simple Python function that takes a list of integers and returns the sum of all elements divisible by 3.
  
  def divisibleBy3(li):
   total = 0
   for num in li:
    if num % 3 == 0:
     total += num
   return total
  
  assert divisibleBy3([4, 6, 17, 24, 5, 9])==24
  assert divisibleBy3([3, 15, 7, 9, 12])==39
  assert divisibleBy3([2, 4, 8, 10])==0
  assert divisibleBy3([9, 18, 27])==54
  assert divisibleBy3([])==0
output: def divisibleBy3(li):
   total = 0
   for num in li:
    if num % 3 == 0:
     total += num
   return total