func (this *Lexer) Errorf(format string, args ...interface{}) LexFn {
	this.Tokens <- lexertoken.Token{
		Type:  lexertoken.TOKEN_ERROR,
		Value: fmt.Sprintf(format, args...),
	}
	return nil
}
/*
Returns a token with error information.
package lexer
import (
	"fmt"
	"unicode"
	"unicode/utf8"
	"github.com/adampresley/sample-ini-parser/services/lexer/lexertoken"
)
type Lexer struct {
	Name   string
	Input  string
	Tokens chan lexertoken.Token
	State  LexFn
	Start int
	Pos   int
	Width int
}
func (this *Lexer) Backup() {
	this.Pos -= this.Width
}
func (this *Lexer) CurrentInput() string {
	return this.Input[this.Start:this.Pos]
}
func (this *Lexer) Dec() {
	this.Pos--
}
func (this *Lexer) Emit(tokenType lexertoken.TokenType) {
	this.Tokens <- lexertoken.Token{Type: tokenType, Value: this.Input[this.Start:this.Pos]}
	this.Start = this.Pos
}