Accessing IDs of non-filled voxels

**Is your feature request related to a problem? Please describe.**
As per the voxelization tutorial, I can visualize the voxels which are intersecting with elements. How can I visualize voxels which do not have any intersecting elements (i.e. voxels whose values are set to 0)

Below is the snippet taken from the documentation:
_Open3D provides the method create_from_triangle_mesh that creates a voxel grid from a triangle mesh. It returns a voxel grid where all voxels that are intersected by a triangle are set to 1, **all others are set to 0**. The argument voxel_size defines the resolution of the voxel grid._

`print('input')
mesh = o3dtut.get_bunny_mesh()
mesh.scale(1 / np.max(mesh.get_max_bound() - mesh.get_min_bound()),
center=mesh.get_center())
o3d.visualization.draw_geometries([mesh])
print('voxelization')
voxel_grid = o3d.geometry.VoxelGrid.create_from_triangle_mesh(mesh,
voxel_size=0.05)`

**Describe the solution you'd like**
Going through the geometry.VoxelGrid API, I cannot access the variable in which such 'intersection' value is stored. So, exposing it will help.

**Describe alternatives you've considered**

**Additional context**