docs: def formatSI(n) -> str:
      """
      Format the integer or float n to 3 significant digits + SI prefix.
      """
      s = ''
      if n < 0:
          n = -n
          s += '-'
      if type(n) is int and n < 1000:
          s = str(n) + ' '
      elif n < 1e-22:
          s = '0.00 '
      else:
          assert n < 9.99e26
          log = int(math.floor(math.log10(n)))
          i, j = divmod(log, 3)
          for _try in range(2):
              templ = '%.{}f'.format(2 - j)
              val = templ % (n * 10 ** (-3 * i))
              if val != '1000':
                  break
              i += 1
              j = 0
          s += val + ' '
          if i != 0:
              s += 'yzafpnum kMGTPEZY'[i + 8]
      return s