# File lib/backports/1.9.3/io.rb, line 4
  def advise(advice, offset=0, len=0)
    case advice
    when  :normal,
          :sequential,
          :random,
          :willneed,
          :dontneed,
          :noreuse
      return nil
    when Symbol
      raise NotImplementedError, "Unsupported advice #{advice}"
    else
      raise TypeError, "advice must be a Symbol"
    end
  end