code: def unique(seq):
      '''
      https://stackoverflow.com/questions/480214/how-do-you-remove-duplicates-from-a-list-in-whilst-preserving-order
      '''
      has = []
      return [x for x in seq if not (x in has or has.append(x))f unique(seq):
      '''
      https://stackoverflow.com/questions/480214/how-do-you-remove-duplicates-from-a-list-in-whilst-preserving-order
      '''
      has = []
      return [x for x in seq if not (x in has or has.append(x))]
docs: https://stackoverflow.com/questions/480214/how-do-you-remove-duplicates-from-a-list-in-whilst-preserving-order