Here is the old way.
Here is the obvious query to look for unread emails in your primary inbox. If primary was a official category this would be a tiny bit easier.
is:unread -category:(social promotions updates forums) in:inbox
Notes from the talk Programming the Feynman Way way by Ben Evans.
Points I found interesting:
The purpose of Agile: give order of magnitude increase in productivity.
Explicit Assumptions and Approximation. State assumptions up front so when gaining data they are confirmed, adjusted, or changed.
Empirical view of the problem. With data you can start to use the data points to eliminate any conclusion that does not fit the data. Utilise Occams Razor: the simplest explanation is most likely correct. The more data the more conclusions you can also discount as not fitting the data.
Hardware people have been doing great strides in computing power but software is getting more complex. Moores law is running out. Understanding hardware and computing theories such as big-O will be increasingly important.