docs: def seconds2str(seconds):
      """Returns string such as 1h 05m 55s."""
  
      if seconds < 0:
          return "{0:.3g}s".format(seconds)
      elif math.isnan(seconds):
          return "NaN"
      elif math.isinf(seconds):
          return "Inf"
  
      m, s = divmod(seconds, 60)
      h, m = divmod(m, 60)
      if h >= 1:
          return "{0:g}h {1:02g}m {2:.3g}s".format(h, m, s)
      elif m >= 1:
          return "{0:02g}m {1:.3g}s".format(m, s)
      else:
          return "{0:.3g}s".format(s)