input: Write a Python function to determine whether a given list of integers is sorted in ascending order. The function should return False if any number appears more than twice in the list. The list will consist of non-negative integers only.
  
  assert is_ordered([5]) == True
  assert is_ordered([1, 2, 3, 4, 5]) == True
  assert is_ordered([1, 3, 2, 4, 5]) == False
  assert is_ordered([1, 2, 3, 4, 5, 6]) == True
  assert is_ordered([1, 2, 3, 4, 5, 6, 7]) == True
  assert is_ordered([1, 3, 2, 4, 5, 6, 7]) == False
  assert is_ordered([]) == True
  assert is_ordered([1]) == True
  assert is_ordered([3, 2, 1]) == False
  assert is_ordered([1, 2, 2, 2, 3, 4]) == False
  assert is_ordered([1, 2, 3, 3, 3, 4]) == False
  assert is_ordered([1, 2, 2, 3, 3, 4]) == True
  assert is_ordered([1, 2, 3, 4]) == True
output: def is_ordered(lst):
      if any(lst.count(x) > 2 for x in lst):
          return False
      return lst == sorted(lst)