input: 
  def removeDuplicates(arr):
      result = []
  
      # traverse for all elements
      for i in arr:
  
          # check if exists in result
          if i not in result:
              result.append(i)
  
      # return result
      return result
  
  """
  >>> removeDuplicates(['a', 'b', 'a', 'c', 'c', 'd'])
  ['a', 'b', 'c', 'd']
  >>> removeDuplicates(['one', 'two', 'three', 'two', 'one', 'four'])
  ['one', 'two', 'three', 'four']
  """
  
output:     return result