input: Write a function to remove duplicates from a given array of strings and return the resulting array. If the given array is empty then return an empty array.
  assert removeDuplicates(['a', 'b', 'a', 'c', 'c', 'd'])==['a', 'b', 'c', 'd']
  assert removeDuplicates(['hello', 'world', 'hello'])==['hello', 'world']
  assert removeDuplicates(['1', '2', '3', '1', '2'])==['1', '2', '3']
  assert removeDuplicates([])==[]
output: def removeDuplicates(arr):
      return list(dict.fromkeys(arr))