_isValid(chip) {
      if (chip.hasOwnProperty('tag') && chip.tag !== '') {
        let exists = false;
        for (let i = 0; i < this.chipsData.length; i++) {
          if (this.chipsData[i].tag === chip.tag) {
            exists = true;
            break;
          }
        }
        return !exists;
      }

      return false;
    }
Check if chip is valid
@param {chip} chip