handleTimer(evt){
      const id=evt.target.id;
      clearInterval(this.Interval)
      this.Interval=setInterval(() => {
        let timer=this.state.timer;
        if(timer > 0){
          this.setState({
            timer: this.state.timer - 1
          })
        }else if(id==="reset"){
     clearInterval(this.Interval);
     this.setState((state) => ({
      session: 25, timer:1500, break:5, isRunning:false}))
        }
        else{
          clearInterval(this.Interval)}
      },1000)}