input: Write a function to remove all duplicates from a given array of strings and return the resulting array.
  assert removeDuplicates(['a', 'b', 'a', 'c', 'c', 'd'])==['a', 'b', 'c', 'd']
  assert removeDuplicates(['apple', 'banana', 'banana', 'cherry', 'apple'])==['apple', 'banana', 'cherry']
  assert removeDuplicates(['x', 'y', 'x', 'z', 'z', 'y'])==['x', 'y', 'z']
  assert removeDuplicates([])==[]
  assert removeDuplicates(['unique'])==['unique']
output: def removeDuplicates(arr):
      return list(dict.fromkeys(arr))