input: Write a function to remove duplicate entries from a given list. If the list is empty, return an empty list.
  assert removeDuplicates([1, 2, 2, 3, 3, 4])==[1, 2, 3, 4]
  assert removeDuplicates([5, 5, 5, 5])==[5]
  assert removeDuplicates([])==[]
  assert removeDuplicates([1, 1, 2, 3, 4, 4])==[1, 2, 3, 4]
output: def removeDuplicates(lst):
      return list(dict.fromkeys(lst))