How to use the @pixi/math.Matrix.IDENTITY function in @pixi/math

constructor(uSampler, options)
    {
        const uniforms = {
            uSampler,
            alpha: 1,
            uTextureMatrix: Matrix.IDENTITY,
            uColor: new Float32Array([1, 1, 1, 1]),
        };

        // Set defaults
        options = Object.assign({
            tint: 0xFFFFFF,
            alpha: 1,
            pluginName: 'batch',
        }, options);

        if (options.uniforms)
        {
            Object.assign(uniforms, options.uniforms);
        }

        super(options.program || Program.from(vertex, fragment), uniforms);

// probably only need to set once!
        // as its then a reference..
        if (mesh.shader.program.uniformData.translationMatrix)
        {
            // the transform!
            mesh.shader.uniforms.translationMatrix = mesh.transform.worldTransform.toArray(true);
        }
        if (mesh.shader.uniforms.uTextureMatrix)
        {
            if (mesh.uploadUvMatrix)
            {
                mesh.shader.uniforms.uTextureMatrix = mesh.uvMatrix.mapCoord.toArray(true);
            }
            else
            {
                mesh.shader.uniforms.uTextureMatrix = Matrix.IDENTITY.toArray(true);
            }
        }

        // bind and sync uniforms..
        this.renderer.shader.bind(mesh.shader);

        // set state..
        this.renderer.state.setState(mesh.state);

        // bind the geometry...
        this.renderer.geometry.bind(mesh.geometry, mesh.shader);
        // then render it
        this.renderer.geometry.draw(mesh.drawMode, mesh.size, mesh.start, mesh.geometry.instanceCount);
    }
}

calculateBounds()
    {
        const bounds = this._bounds;
        const sequenceBounds = tmpBounds;
        let curMatrix = Matrix.IDENTITY;

        this._bounds.clear();
        sequenceBounds.clear();

        for (let i = 0; i < this.graphicsData.length; i++)
        {
            const data = this.graphicsData[i];
            const shape = data.shape;
            const type = data.type;
            const lineStyle = data.lineStyle;
            const nextMatrix = data.matrix || Matrix.IDENTITY;
            let lineWidth = 0.0;

            if (lineStyle && lineStyle.visible)
            {
                const alignment = lineStyle.alignment;

calculateBounds()
    {
        const bounds = this._bounds;
        const sequenceBounds = tmpBounds;
        let curMatrix = Matrix.IDENTITY;

        this._bounds.clear();
        sequenceBounds.clear();

        for (let i = 0; i < this.graphicsData.length; i++)
        {
            const data = this.graphicsData[i];
            const shape = data.shape;
            const type = data.type;
            const lineStyle = data.lineStyle;
            const nextMatrix = data.matrix || Matrix.IDENTITY;
            let lineWidth = 0.0;

            if (lineStyle && lineStyle.visible)
            {
                const alignment = lineStyle.alignment;

                lineWidth = lineStyle.width;

                if (type === SHAPES.POLY)
                {
                    lineWidth = lineWidth * (0.5 + Math.abs(0.5 - alignment));
                }
                else
                {
                    lineWidth = lineWidth * Math.max(0, alignment);
                }