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: scalar.go
    path of file: ./repos/gallium/vendor/github.com/alexflint/go-arg
    
    the code of the file until where you have to start completion: package arg

import (
	"encoding"
	"fmt"
	"net"
	"net/mail"
	"reflect"
	"strconv"
	"time"
)

// The reflected form of some special types
var (
	textUnmarshalerType = reflect.TypeOf([]encoding.TextUnmarshaler{}).Elem()
	durationType        = reflect.TypeOf(time.Duration(0))
	mailAddressType     = reflect.TypeOf(mail.Address{})
	ipType              = reflect.TypeOf(net.IP{})
	macType             = reflect.TypeOf(net.HardwareAddr{})
)

// isScalar returns true if the type can be parsed from a single string
func isScalar(t reflect.Type) (scalar, boolean bool) {
	// If it implements encoding.TextUnmarshaler then use that
	if t.Implements(textUnmarshalerType) {
		// scalar=YES, boolean=NO
		return true, false
	}

	// If we have a pointer then dereference it
	if t.Kind() == reflect.Ptr {
		t = t.Elem()
	}

	// Check for other special types
	switch t {
	case durationType, mailAddressType, ipType, macType:
		// scalar=YES, boolean=NO
		return true, false
	}

	// Fall back to checking the kind
	switch t.Kind() {
	case reflect.Bool:
		// scalar=YES, boolean=YES
		return true, true
	case reflect.String, reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,

    
func setScalar(v reflect.Value, s string) error {
	if !v.CanSet() {
		return fmt.Errorf("field is not exported")
	}

	// If we have a nil pointer then allocate a new object
	if v.Kind() == reflect.Ptr && v.IsNil() {
		v.Set(reflect.New(v.Type().Elem()))
	}

	// Get the object as an interface
	scalar := v.Interface()

	// If it implements encoding.TextUnmarshaler then use that
	if scalar, ok := scalar.(encoding.TextUnmarshaler); ok {
		return scalar.UnmarshalText([]byte(s))
	}

	// If we have a pointer then dereference it
	if v.Kind() == reflect.Ptr {
		v = v.Elem()
	}

	// Switch on concrete type
	switch scalar.(type) {
	case time.Duration:
		duration, err := time.ParseDuration(s)
		if err != nil {
			return err
		}
		v.Set(reflect.ValueOf(duration))
		return nil
	case mail.Address:
		addr, err := mail.ParseAddress(s)
		if err != nil {
			return err
		}
		v.Set(reflect.ValueOf(*addr))
		return nil
	case net.IP:
		ip := net.ParseIP(s)
		if ip == nil {
			return fmt.Errorf(`invalid IP address: "%s"`, s)
		}
		v.Set(reflect.ValueOf(ip))
		return nil
	case net.HardwareAddr:
		ip, err := net.ParseMAC(s)
		if err != nil {
			return err
		}
		v.Set(reflect.ValueOf(ip))
		return nil
	}

	// Switch on kind so that we can handle derived types
	switch v.Kind() {
	case reflect.String:
		v.SetString(s)
	case reflect.Bool:
		x, err := strconv.ParseBool(s)
		if err != nil {
			return err
		}
		v.SetBool(x)
	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
		x, err := strconv.ParseInt(s, 10, v.Type().Bits())
		if err != nil {
			return err
		}
		v.SetInt(x)
	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
		x, err := strconv.ParseUint(s, 10, v.Type().Bits())
		if err != nil {
			return err
		}
		v.SetUint(x)
	case reflect.Float32, reflect.Float64:
		x, err := strconv.ParseFloat(s, v.Type().Bits())
		if err != nil {
			return err
		}
		v.SetFloat(x)
	default:
		return fmt.Errorf("cannot parse argument into %s", v.Type().String())
	}
	return nil
}