Instructor Notes

• This exercise is intended to replace the Protobuf parsing exercise from the original version.

• All tests except test_drop_first_sentence_before_second can pass with only a single lifetime specifier on Difference. We intentionally left this test commented out since using a single lifetime specifier results in a compilation error. When going over the solution, it is worth showing this to students.

• You can ask students who finish early to come up with additional tests that would fail to compile with a single lifetime specifier on Difference.