func (l *Logger) Printf(format string, v ...interface{}) {
	l.output(fmt.Sprintf(format, v...))
}
Printf prints the plain text.
package reports
import (
	"fmt"
	"io"
	"os"
)
type Logger struct {
	out io.Writer  
	buf []byte     
}
func NewLogger(out io.Writer) *Logger {
	return &Logger{out: out}
}
func (l *Logger) SetOut(out io.Writer) {
	l.out = out
}
func (l *Logger) Run(format string, v ...interface{}) {
	s := fmt.Sprintf(format, v...)
	if len(s) > 0 && s[len(s)-1] == '\n' {
		s = s[:len(s)-1]
	}
	l.output("[ ] " + s)
}
func (l *Logger) Ok() {
	l.outputln("\r[✓]")
}
func (l *Logger) Nok() {
	l.outputln("\r[✗]")
}