I'm very new to Mathematica and am currently trying the VertexDelete function, but after using it, my graph isn't drawing.

Input:

```
a = CompleteGraph[{7, 2}]
a = VertexDelete[a, {3, 4}]

```

As the output I get

```
Graph["small default graph picture", vertex count:7 and edge count:10]

```

The vertex count and edge count are correct, so the removal is done, but why doesn't it evaluate to a graph drawing?