How to use the transformation-matrix.identity function in transformation-matrix

const _parseTransform = function (domElement) {
    let matrix = Matrix.identity();
    const string = domElement.attributes && domElement.attributes.transform && domElement.attributes.transform.value;
    if (!string) return matrix;
    // https://www.w3.org/TR/SVG/types.html#DataTypeTransformList
    // Parse SVG transform string. First we split at /)\s*/, to separate
    // commands
    const transforms = string.split(/\)\s*/g);
    for (const transform of transforms) {
        if (!transform) break;
        // Command come before the '(', values after
        const parts = transform.split(/\(\s*/);
        const command = parts[0].trim();
        const v = parts[1].split(/[\s,]+/g);
        // Convert values to floats
        for (let j = 0; j < v.length; j++) {
            v[j] = parseFloat(v[j]);
        }

const transformStrokeWidths = function (svgTag, windowRef, bboxForTesting) {
    const inherited = Matrix.identity();
    const applyTransforms = (element, matrix, strokeWidth, fill) => {
        if (_isContainerElement(element)) {
            // Push fills and stroke width down to leaves
            if (element.attributes['stroke-width']) {
                strokeWidth = element.attributes['stroke-width'].value;
            }
            if (element.attributes && element.attributes.fill) {
                fill = element.attributes.fill.value;
            }

            // If any child nodes don't take attributes, leave the attributes
            // at the parent level.
            for (let i = 0; i < element.childNodes.length; i++) {
                applyTransforms(
                    element.childNodes[i],
                    Matrix.compose(matrix, _parseTransform(element)),

test('testMatrix', () => {
  const value = getDefaultValue(
    200, 200,       //viewer 200x200
    0, 0, 400, 400, //svg 400x400
  )

  const matrix = testMatrix(value)
  expect(matrix).toEqual(identity())
  expect(matrix).toMatchSnapshot()
})

export function reset(value) {
  return set(value, _extends({
    mode: MODE_IDLE
  }, identity()));
}

export function reset(value) {
  return set(value, {
    mode: MODE_IDLE,
    ...identity()
  });
}

constructor(matrix) {
    this.matrix = matrix || identity();
  }

_this.minZoomLevel = 0.1;
        _this.maxZoomLevel = 4.0;
        _this.autoZoom = false;
        _this.panOnZoom = true;
        _this.autoCenter = false;
        _this.activate = new EventEmitter();
        _this.deactivate = new EventEmitter();
        _this.subscriptions = [];
        _this.margin = [0, 0, 0, 0];
        _this.results = [];
        _this.isPanning = false;
        _this.isDragging = false;
        _this.initialized = false;
        _this.graphDims = { width: 0, height: 0 };
        _this._oldLinks = [];
        _this.transformationMatrix = identity();
        _this._touchLastX = null;
        _this._touchLastY = null;
        _this.groupResultsBy = function (node) { return node.label; };
        return _this;
    }
    Object.defineProperty(GraphComponent.prototype, "zoomLevel", {

export function getDefaultValue(viewerWidth, viewerHeight, SVGWidth, SVGHeight) {
  return set({}, _extends({}, identity(), {
    version: 2,
    mode: MODE_IDLE,
    focus: false,
    viewerWidth: viewerWidth,
    viewerHeight: viewerHeight,
    SVGWidth: SVGWidth,
    SVGHeight: SVGHeight,
    startX: null,
    startY: null,
    endX: null,
    endY: null,
    miniatureOpen: true
  }));
}