I have a dictionary of polyhedra which I want to consider various intersections and unions of. For now, my dictionary has four polyhedra in it. When running the following for loop:

```
poly_int = Polyhedron([b[key] for key in b.keys()]) # this is a tetrahedron containing
# all of my polyhedra
for i in [1,2,3,4]:
poly_int = poly[i] & poly_int
```

I get a very nasty error:

```
AttributeError: 'Polyhedra_RDF_cdd_with_category.element_class'
object has no attribute '_Vrepresentation'
```

(The traceback for the error is quite long. I can include it if needed.)

Manually computing

```
poly[1] & poly[2] & poly[3] & poly[4]
```

gives the same error. HOWEVER, if instead I compute

```
(poly[1] & poly[2]) & (poly[3] & poly[4])
```

I get no errors. While this is a fine workaround for this particular case, I'm scripting these intersections and need some way to actually compute these intersections automatically. Using something like

```
poly[1].intersection(poly[2]) # etc.
```

doesn't help either. Any thoughts?