Checking Boundary Markers?

If I’ve used

bc1.mark(boundaries, 1)
bc2.mark(boundaries, 2)
# etc.

is there a way to, visually or otherwise, verify that what I think is being marked in my domain is being properly marked?

EDIT: I realize that part of the information I’m after is stored in boundaries.array(), having constructed

boundaries = MeshFunction("size_t", mesh, mesh.topology().dim()-1)

As this enumerates the facets of the original mesh, assigning them the markers. I think if I can figure out how to relate the facets, as enumerated in boundaries.array(), to the vertices (or something else) in the underlying mesh, I’ll be able to verify my boundary markers. Does that make sense?

You can save MeshFunction objects to pvd or XDMF and inspect them visually in Paraview or Visit