How to use the zrender/src/core/util.extend function in zrender

export function setTextStyle(textStyle, textStyleModel, specifiedTextStyle, opt, isEmphasis) {
  setTextStyleCommon(textStyle, textStyleModel, opt, isEmphasis);
  specifiedTextStyle && zrUtil.extend(textStyle, specifiedTextStyle); // textStyle.host && textStyle.host.dirty && textStyle.host.dirty(false);

  return textStyle;
}
/**

if (isInit) {
            // Default label emphasis `position` and `show`
            fillLabel(markerOpt);
          }

          zrUtil.each(markerOpt.data, function (item) {
            // FIXME Overwrite fillLabel method ?
            if (item instanceof Array) {
              fillLabel(item[0]);
              fillLabel(item[1]);
            } else {
              fillLabel(item);
            }
          });
          markerModel = new MarkerModel(markerOpt, this, ecModel);
          zrUtil.extend(markerModel, {
            mainType: this.mainType,
            // Use the same series index and name
            seriesIndex: seriesModel.seriesIndex,
            name: seriesModel.name,
            createdBySelf: true
          });
          markerModel.__hostSeries = seriesModel;
        } else {
          markerModel._mergeOption(markerOpt, ecModel, true);
        }

        seriesModel[modelPropName] = markerModel;
      }, this);
    }

}

        mlFrom.coord[valueIndex] = mlTo.coord[valueIndex] = value;

        item = [mlFrom, mlTo, { // Extra option for tooltip and label
            type: mlType,
            valueIndex: item.valueIndex,
            // Force to use the value of calculated value.
            value: value
        }];
    }

    item = [
        markerHelper.dataTransform(seriesModel, item[0]),
        markerHelper.dataTransform(seriesModel, item[1]),
        zrUtil.extend({}, item[2])
    ];

    // Avoid line data type is extended by from(to) data type
    item[2].type = item[2].type || '';

    // Merge from option and to option into line option
    zrUtil.merge(item[2], item[0]);
    zrUtil.merge(item[2], item[1]);

    return item;
};

}

    opt = opt || {};
    sysDims = (sysDims || []).slice();
    var dimsDef = (opt.dimsDef || []).slice();
    var encodeDef = createHashMap(opt.encodeDef);
    var dataDimNameMap = createHashMap();
    var coordDimNameMap = createHashMap();
    // var valueCandidate;
    var result = [];

    var dimCount = getDimCount(source, sysDims, dimsDef, opt.dimCount);

    // Apply user defined dims (`name` and `type`) and init result.
    for (var i = 0; i < dimCount; i++) {
        var dimDefItem = dimsDef[i] = extend(
            {}, isObject(dimsDef[i]) ? dimsDef[i] : {name: dimsDef[i]}
        );
        var userDimName = dimDefItem.name;
        var resultItem = result[i] = {otherDims: {}};
        // Name will be applied later for avoiding duplication.
        if (userDimName != null && dataDimNameMap.get(userDimName) == null) {
            // Only if `series.dimensions` is defined in option
            // displayName, will be set, and dimension will be diplayed vertically in
            // tooltip by default.
            resultItem.name = resultItem.displayName = userDimName;
            dataDimNameMap.set(userDimName, i);
        }
        dimDefItem.type != null && (resultItem.type = dimDefItem.type);
        dimDefItem.displayName != null && (resultItem.displayName = dimDefItem.displayName);
    }

if (!axisModel.get('axisLine.show')) {
            return;
        }

        var extent = this.axisModel.axis.getExtent();

        var matrix = this._transform;
        var pt1 = [extent[0], 0];
        var pt2 = [extent[1], 0];
        if (matrix) {
            v2ApplyTransform(pt1, pt1, matrix);
            v2ApplyTransform(pt2, pt2, matrix);
        }

        var lineStyle = extend(
            {
                lineCap: 'round'
            },
            axisModel.getModel('axisLine.lineStyle').getLineStyle()
        );

        this.group.add(new graphic.Line({
            // Id for animation
            anid: 'line',
            subPixelOptimize: true,
            shape: {
                x1: pt1[0],
                y1: pt1[1],
                x2: pt2[0],
                y2: pt2[1]
            },

function mergeNewElOptionToExist(existList, index, newElOption) {
    // Update existing options, for `getOption` feature.
    var newElOptCopy = zrUtil.extend({}, newElOption);
    var existElOption = existList[index];

    var $action = newElOption.$action || 'merge';
    if ($action === 'merge') {
        if (existElOption) {

            if (__DEV__) {
                var newType = newElOption.type;
                zrUtil.assert(
                    !newType || existElOption.type === newType,
                    'Please set $action: "replace" to change `type`'
                );
            }

            // We can ensure that newElOptCopy and existElOption are not
            // the same object, so `merge` will not change newElOptCopy.

function mergeNewElOptionToExist(existList, index, newElOption) {
  // Update existing options, for `getOption` feature.
  var newElOptCopy = zrUtil.extend({}, newElOption);
  var existElOption = existList[index];
  var $action = newElOption.$action || 'merge';

  if ($action === 'merge') {
    if (existElOption) {
      // We can ensure that newElOptCopy and existElOption are not
      // the same object, so `merge` will not change newElOptCopy.
      zrUtil.merge(existElOption, newElOptCopy, true); // Rigid body, use ignoreSize.

      layoutUtil.mergeLayoutParam(existElOption, newElOptCopy, {
        ignoreSize: true
      }); // Will be used in render.

      layoutUtil.copyLayoutParams(newElOption, existElOption);
    } else {
      existList[index] = newElOptCopy;

function prepareAnimationWhenHasOld(lasts, element, storageName) {
    var lastCfg = lasts[thisRawIndex] = {};
    lastCfg.old = storageName === 'nodeGroup' ? element.position.slice() : zrUtil.extend({}, element.shape);
  } // If a element is new, we need to find the animation start point carefully,
  // otherwise it will looks strange when 'zoomToNode'.

function getCleanedElOption(elOption) {
    elOption = zrUtil.extend({}, elOption);
    zrUtil.each(
        ['id', 'parentId', '$action', 'hv', 'bounding'].concat(layoutUtil.LOCATION_PARAMS),
        function (name) {
            delete elOption[name];
        }
    );
    return elOption;
}

function getAnimatableProps(el) {
        var obj = {
            position: vector.clone(el.position),
            rotation: el.rotation
        };
        if (el.shape) {
            obj.shape = zrUtil.extend({}, el.shape);
        }
        return obj;
    }
    var elMap1 = getElMap(g1);