input: Write a python function to find the second largest number in a given list.
  assert find_second_largest_number([2, 10, 7, 5, 8]) == 8
  assert find_second_largest_number([1, 2, 3, 4, 5]) == 4
  assert find_second_largest_number([10, 10, 9, 8, 8, 7]) == 9
output: def find_second_largest_number(lst):
      first, second = float('-inf'), float('-inf')
      for num in lst:
          if num > first:
              first, second = num, first
          elif first > num > second:
              second = num
      return second