def METHOD_NAME(self):
    # =======================
    # VOXEL GRID FILTER
    # =======================
    req = FilterCloud.Request()
    req.pcdfilename = self.pcdfilename
    req.operation = py_perception.srv.FilterCloud.Request.VOXELGRID
    # FROM THE SERVICE, ASSIGN POINTS
    req.input_cloud = PointCloud2()
    # ERROR HANDLING
    if req.pcdfilename == '':
        self.get_logger().error('No file parameter found')
        return
    # PACKAGE THE FILTERED POINTCLOUD2 TO BE PUBLISHED
    future = self.client.call_async(req)
    rclpy.spin_until_future_complete(self, future)
    res_voxel = future.result()
    if not res_voxel.success:
        self.get_logger().error('Unsuccessful voxel grid filter operation')
        return
    # PUBLISH VOXEL FILTERED POINTCLOUD2
    self.voxel_pub.publish(res_voxel.output_cloud)
    self.last_cloud = res_voxel
    self.get_logger().info("published: voxel grid filter response")