code: def unique(input_list):
      
      output = []
      for item in input_list:
          if item not in output:
              output.append(item)
      return output
docs: Return a list of unique items (similar to set functionality).
  
      Parameters
      ----------
      input_list : list
          A list containg some items that can occur more than once.
  
      Returns
      -------
      list
          A list with only unique occurances of an item.