code: func (stream *Stream) WriteInt32(nval int32) {
  	var val uint32
  	if nval < 0 {
  		val = uint32(-nval)
  		stream.buf = append(stream.buf, '-')
  	} else {
  		val = uint32(nval)
  	}
  	stream.WriteUint32(val)
  }
docs: // WriteInt32 write int32 to stream