input: Write a function to find the maximum number from a list of non-negative integers. Return the maximum number found. If the list is empty, return 0.
  assert find_max([1, 3, 12, 5, 8, 10])==12
  assert find_max([0, 0, 0])==0
  assert find_max([5])==5
  assert find_max([])==0
  assert find_max([2, 4, 6, 8, 10])==10
output: def find_max(lst):
      if not lst:
          return 0
      return max(lst)