You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: decode.go
    path of file: ./repos/learning/golang/source_code/gopl.io/ch12/sexpr
    
    the code of the file until where you have to start completion: // Copyright Â© 2016 Alan A. A. Donovan & Brian W. Kernighan.
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/

// See page 344.

// Package sexpr provides a means for converting Go objects to and
// from S-expressions.
package sexpr

import (
	"bytes"
	"fmt"
	"reflect"
	"strconv"
	"text/scanner"
)

//!+Unmarshal
// Unmarshal parses S-expression data and populates the variable
// whose address is in the non-nil pointer out.
fu
    
func read(lex *lexer, v reflect.Value) {
	switch lex.token {
	case scanner.Ident:
		// The only valid identifiers are
		// "nil" and struct field names.
		if lex.text() == "nil" {
			v.Set(reflect.Zero(v.Type()))
			lex.next()
			return
		}
	case scanner.String:
		s, _ := strconv.Unquote(lex.text()) // NOTE: ignoring errors
		v.SetString(s)
		lex.next()
		return
	case scanner.Int:
		i, _ := strconv.Atoi(lex.text()) // NOTE: ignoring errors
		v.SetInt(int64(i))
		lex.next()
		return
	case '(':
		lex.next()
		readList(lex, v)
		lex.next() // consume ')'
		return
	}
	panic(fmt.Sprintf("unexpected token %q", lex.text()))
}