code: def readable_size(C, bytes, suffix='B', decimals=1, sep='\u00a0'):
          
          if bytes is None:
              return
          size = float(bytes)
          for unit in C.SIZE_UNITS:
              if abs(size) < 1024 or unit == C.SIZE_UNITS[-1]:
                  return "{size:.{decimals}f}{sep}{unit}{suffix}".format(
                      size=size,
                      unit=unit,
                      suffix=suffix,
                      sep=sep,
                      decimals=C.SIZE_UNITS.index(unit) > 0 and decimals or 0,  # B with no decimal
                  )
              size /= 1024
docs: given a number of bytes, return the file size in readable units