code: def uniqify(seq):
      
  
      if PY37:
          # Credit: Raymond Hettinger
          return list(dict.fromkeys(seq))
      else:
          # Credit: Dave Kirby
          # https://www.peterbe.com/plog/uniqifiers-benchmark
          seen = set()
          # We don't care about truth value of `not seen.add(x)`;
          # just there to add to `seen` inplace.
          return [x for x in seq if x not in seen and not seen.add(x)]
docs: `Uniqify` a sequence, preserving order.
  
      A plain-vanilla version of itertools' `unique_everseen`.
  
      Example
      -------
      >>> s = list('zyxabccabxyz')
      >>> uniqify(s)
      ['z', 'y', 'x', 'a', 'b', 'c'
  
      Returns
      -------
      list