code: func (p *Parser) scan() {
  	for {
  		token, literal := p.l.Lex()
  		p.scannedItems = append(p.scannedItems, ScannedItem{token, literal})
  		if token == EndOfStringToken {
  			break
  		}
  	}
  }
docs: // scan runs through the input string and stores the ScannedItem in an array
  // Parser can now lookahead and consume the tokens