code: def argmin(seq, fn):
      
      best = seq[0]; best_score = fn(best)
      for x in seq:
          x_score = fn(x)
          if x_score < best_score:
              best, best_score = x, x_score
      return best
docs: Return an element with lowest fn(seq[i]) score; tie goes to first one.
      >>> argmin(['one', 'to', 'three'], len)
      'to'