class IO

def advise(advice, offset=0, len=0)
  raise RangeError if Backports.coerce_to_int(offset) >= 1<<31
  raise RangeError if Backports.coerce_to_int(len) >= 1<<31
  raise IOError if closed?
  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

def each_char
  return to_enum(:each_char) unless block_given?
  if $KCODE == "UTF-8"
    lookup = 7.downto(4)
    while c = read(1) do
      n = c[0]
      leftmost_zero_bit = lookup.find{|i| n[i].zero? }
      case leftmost_zero_bit
      when 7 # ASCII
        yield c
      when 6 # UTF 8 complementary characters
        next # Encoding error, ignore
      else
        more = read(6-leftmost_zero_bit)
        break unless more
        yield c+more
      end
    end
  else
    while s = read(1)
      yield s
    end
  end
  self
end