input: Write a function to remove all duplicate elements from a given list while preserving the original order. If the input list is empty, the function should return an empty list.
  
  
  def remove_duplicates(nums):
      new_list = []
      for num in nums:
          if num not in new_list:
              new_list.append(num)
      return new_list
  
  # Test cases
  assert remove_duplicates([1, 3, 3, 5, 5, 7]) == [1, 3, 5, 7]
  assert remove_duplicates([4, 4, 4, 4]) == [4]
  assert remove_duplicates([1, 2, 3, 4]) == [1, 2, 3, 4]
  assert remove_duplicates([]) == []
  
output: def remove_duplicates(nums):
      new_list = []
      for num in nums:
          if num not in new_list:
              new_list.append(num)
      return new_list