input: Write a function to remove all duplicate elements from a list while preserving the original order. The function should take a single list as an argument and return a new list with all duplicates removed.
  
  def remove_duplicates(nums):
    new_list = []
    for num in nums:
      if num not in new_list:
        new_list.append(num) 
    return new_list
  
  assert remove_duplicates([1, 3, 3, 5, 5, 7]) == [1, 3, 5, 7
output: def remove_duplicates(nums):
    new_list = []
    for num in nums:
      if num not in new_list:
        new_list.append(num) 
    return new_list