A memory leaking code example (for best practice with AngularJS) ?

GO HERE.
At the bottom ("Accessing the backend") let's look into the file "finance3.js".
Do you see there this line: usdToForeignRates = newUsdToForeignRates; ?
If I understood the things correctly, this is a good memory-leak, huh? Or not?

"We are a team of college students working on this project like it's our full time job."

Guys, guys, guys... Take it easy! I have a full time job and am working as if I am a college student ;)