How to use the @microsoft/sp-lodash-subset.get function in @microsoft/sp-lodash-subset

private onCustomPropertyPaneChange(propertyPath: string, newValue: any): void {
    Log.verbose(this.logSource, "WebPart property '" + propertyPath + "' has changed, refreshing WebPart...", this.context.serviceScope);
    let rerenderTemplateTextDialog = false;
    const oldValue = get(this.properties, propertyPath);
    
    // Stores the new value in web part properties
    update(this.properties, propertyPath, (): any => { return newValue; });
    this.onPropertyPaneFieldChanged(propertyPath, oldValue, newValue);

    // Resets dependent property panes if needed
    this.resetDependentPropertyPanes(propertyPath);

    // If the viewfields have changed, update the default template text if it hasn't been altered by the user
    if(propertyPath == ContentQueryConstants.propertyViewFields && !this.properties.hasDefaultTemplateBeenUpdated) {
      let generatedTemplate = this.ContentQueryService.generateDefaultTemplate(newValue);
      update(this.properties, ContentQueryConstants.propertyTemplateText, (): any => { return generatedTemplate; });
      this.templateTextDialog.properties.dialogTextFieldValue = generatedTemplate;
      rerenderTemplateTextDialog = true;
    }

private onListChange(propertyPath: string, oldValue: any, newValue: any): void {
    //update the property value
    update(this.properties, propertyPath, (): any => { return newValue; });

    // trigger that propertyPath was changed
    this.onPropertyPaneFieldChanged(propertyPath, oldValue, newValue);

    // reset selected item
    const oldItemValue : any = get(this.properties, 'item');
    this.properties.item = undefined;
    update(this.properties, 'item', (): any => { return this.properties.item; });

    // store selected item reset in web part properties
    this.onPropertyPaneFieldChanged('item', oldItemValue, this.properties.item);

    // reset selected values in item dropdown
    //this.itemsDropDown.properties.selectedKey = this.properties.item;
    this.itemsDropDown.properties.selectedKey = "";

    // allow to load items
    this.itemsDropDown.properties.disabled = false;

    // load items and re-render items dropdown
    this.itemsDropDown.render();
  }

private onListChange(propertyPath: string, newValue: any): void {
    const oldValue: any = get(this.properties, propertyPath);
    if (oldValue !== newValue) {
      this.properties.fields = null;
    }
    // store new value in web part properties
    update(this.properties, propertyPath, (): any => newValue);
    // refresh property Pane
    this.context.propertyPane.refresh();
    // refresh web part
    this.render();
  }