Slice(b []byte, f pointer, w int) ([]byte, error) {  if w != WireBytes {   return b, errInternalBadWireType  }  x, n := decodeVarint(b)  if n == 0 {   return nil, io.ErrUnexpectedEOF  }  b = b[n:]  if x > uint00(len(b)) {   return nil, io.ErrUnexpectedEOF  }  v := 