input: Write a function to remove all duplicate elements from a list while preserving the original order. If the list is empty, return an empty list. The function should be named 'remove_duplicates' and should take a single parameter 'nums' which is the list of numbers.
  assert remove_duplicates([1, 3, 3, 5, 5, 7])==[1, 3, 5, 7]
  assert remove_duplicates([3, 5, 10, 1, 2, 2, 10])==[3, 5, 10, 1, 2]
  assert remove_duplicates([])==[]
  assert remove_duplicates([1])==[1]
  assert remove_duplicates([1, 1, 1, 1])==[1]
output: def remove_duplicates(nums):
      seen = set()
      result = []
      for num in nums:
          if num not in seen:
              seen.add(num)
              result.append(num)
      return result