iOS Unit Testing by Example: wait(timeout: ) call on page 162

In the print version of this text, on page 162 right before the second code sample toward the bottom of the page, the book states to add a `wait(timeout:) in the completion handler.

The subsequent example shows that the call should be to waitForExpectations(timeout: ) which is a small detail but since wait(for:timeout:) is an actual method, it was a bit confusing when going through the example initially.