input: Write a function to remove all duplicates from an array of strings and return the resulting array. If the array is empty or contains no duplicates, return the original array.
  assert removeDuplicates(['a', 'b', 'a', 'c', 'c', 'd'])==['a', 'b', 'c', 'd']
  assert removeDuplicates(['apple', 'banana', 'apple'])==['apple', 'banana']
  assert removeDuplicates([])==[]
  assert removeDuplicates(['unique'])==['unique']
  assert removeDuplicates(['same', 'same'])==['same']
output: def removeDuplicates(arr):
      seen = set()
      result = []
      for item in arr:
          if item not in seen:
              seen.add(item)
              result.append(item)
      return result if result else arr