Your task: to write a program which will read in the weather.dat file from this repository and then write a program that will output the day number with the smallest temperature spread (maximum temperature - minimum temperature).

The first column in the file is the day number, the second column in the file is the maximum temperature, and the third column is the minimum temperature.

This task should be completed using test-driven development. As a reminder, Uncle Bob's three rules of TDD are:

1. You are not allowed to write any production code unless it is to make a failing unit test pass.
2. You are not allowed to write any more of a unit test than is suffcient to fail; compilation failures are test failures.
3. You are not allowed to write any more production code than is sufficient to pass the one failing unit test.

We will use the pomodoro method, which means we will work in three 25 minute "sprints" separated by 5 minute breaks.

At the end of the exercise we'll talk through some of the code we've written, and try to match up decisions we made during the writing and testing of the code with the resulting code.