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
  
  # Test cases
  # Example 1
  assert removeDuplicates(['a', 'b', 'a', 'c', 'c', 'd']) == ['a', 'b', 'c', 'd']
  
  # Example 2
  assert removeDuplicates(['apple', 'banana', 'apple', 'banana', 'cherry']) == ['apple', 'banana', 'cherry']
  
  # Example 3
  assert removeDuplicates([]) == []
  
output:     return result