code: func (p *parser) peek() item {
  	if p.peekCount > 0 {
  		return p.token[p.peekCount-1]
  	}
  	p.peekCount = 1
  
  	t := p.lex.nextItem()
  	// Skip comments.
  	for t.typ == ItemComment {
  		t = p.lex.nextItem()
  	}
  	p.token[0] = t
  	return p.token[0]
  }
docs: // peek returns but does not consume the next token.