Why does PyCallGraph2 describe itself while profiling "Hello, World"?

Question

Suppose we have the following file labelled hello.py:

print('Hello, World.')

and we run PyCallGraph on it:

$ pycallgraph graphviz hello.py
Hello, World.

which produces the file pycallgraph.png which we can inspect:

Is there a use case or justification for having pycallgraph2 included in this output?