_prepareClockItems() {
      const values = [];
      let displayStep = this.displayStep;
      let item;
      let valueIndex;
      let i;
      this._items = [];
      for (i = this.itemMin; i <= this.itemMax; i++) {
        values.push({
          "item": i.toString(),
          "innerItem": this.showInnerCircle ? (i + this.itemMax).toString() : undefined
        });
      }
      if (this.lastItemReplacement !== -1) {
        if (this.showInnerCircle && this.prependZero) {
          values[values.length - 1].innerItem = this.lastItemReplacement.toString().padStart(2, "0");
        } else {
          values[values.length - 1].item = this.lastItemReplacement.toString();
        }
      }
      // determines angle step for values display
      const itemStep = 360 / CLOCK_ANGLE_STEP / values.length;
      // determines step for values display in units
      if (this.valueStep * itemStep > displayStep) {
        displayStep = this.valueStep * itemStep;
      }
      for (i = 1; i <= 60; i++) {
        valueIndex = i / itemStep - 1;
        item = i % displayStep !== 0 ? {} : values[valueIndex];
        item.angle = i * CLOCK_ANGLE_STEP;
        item.outerStyles = {
          transform: `translate(-50%) rotate(${i * 6}deg)`
        };
        item.innerStyles = {
          transform: `rotate(-${i * 6}deg)`
        };
        this._items.push(item);
      }
    }
Prepares clock items objects according to current clock settings. Item objects are used for rendering purposes.