class Filesize

def pretty(args = {})
  size = @bytes
  if size < @type[:multiplier]
    unit = "B"
  else
    pos = (Math.log(size) / Math.log(@type[:multiplier])).floor
    pos = @type[:prefixes].size-1 if pos > @type[:prefixes].size - 1
    unit = @type[:prefixes][pos-1] + "B"
  end
  to_s(unit, args)
end