code: func NewBuffer(size int64) (*Buffer, error) {
  	if size <= 0 {
  		return nil, fmt.Errorf("Size must be positive")
  	}
  
  	b := &Buffer{
  		size: size,
  		data: make([]byte, size),
  	}
  	return b, nil
  }
docs: // NewBuffer creates a new buffer of a given size. The size
  // must be greater than 0.