code: def human_bytes(n, unit=None):
      
      if n == 0:
          idx = 0
      elif unit:
          idx = byte_units.index(unit)
      else:
          idx = int(math.floor(math.log(abs(n), 1024)))
          idx = min(idx, len(byte_units))
      return n / 1024. ** idx, byte_units[idx]
docs: Takes a number of bytes *n*, assigns the best matching unit and returns the respective number
      and unit string in a tuple. When *unit* is set, that unit is used. Example:
  
      .. code-block:: python
  
          human_bytes(3407872)
          # -> (3.25, "MB")
  
          human_bytes(3407872, "kB")
          # -> (3328.0, "kB")