input: def removeDuplicates(array):
      """
      Optimize the given function to use built-in functions and remove duplicates from the input list.
      >>> removeDuplicates([1, 2, 2, 3, 4, 4, 5])
      [1, 2, 3, 4, 5]
      >>> removeDuplicates([1, 1, 1, 1])
      [1]
      >>> removeDuplicates([])
      []
      """
output:     return list(dict.fromkeys(array))