code: func NewWriterSize(dest io.Writer, state ws.State, op ws.OpCode, n int) *Writer {
  	if n > 0 {
  		n += headerSize(state, n)
  	}
  	return NewWriterBufferSize(dest, state, op, n)
  }
docs: // NewWriterSize returns a new Writer whose buffer size is at most n + ws.MaxHeaderSize.
  // That is, output frames payload length could be up to n, except the case when
  // Write() is called on empty Writer with len(p) > n.
  //
  // If n <= 0 then the default buffer size is used as Writer's buffer size.