class Sinatra::Helpers::StaticFile

def each
  if @range
    self.pos = @range.begin
    length = @range.end - @range.begin + 1
    while length > 0 && (buf = read([CHUNK_SIZE,length].min))
      yield buf
      length -= buf.length
    end
  else
    rewind
    while buf = read(CHUNK_SIZE)
      yield buf
    end
  end
end