input: Write a function to select and print all elements from a given list that are greater than 50. If the given list is empty, print "No numbers found."
  assert greater_than_50([2, 60, 5, 4, 78, 32, 99])=="60\n78\n99"
  assert greater_than_50([1, 2, 3, 4, 5])=="No numbers found."
  assert greater_than_50([51])=="51"
  assert greater_than_50([])=="No numbers found."
output: def greater_than_50(lst):
      result = [str(num) for num in lst if num > 50]
      if result:
          print("\n".join(result))
      else:
          print("No numbers found.")