A great man once said "I used to be over by the window, and I could see the squirrels, and they were merry." As pleasing of a sight as that was, what if the squirrels weren't merry?

Grady had an unpleasant experience with bushy-tailed rodents at a former job. Before starting at the Fintech firm as a data scientist, he was assured the Business Intelligence department was very advanced and run by an expert. They needed Grady to manipulate large data sets and implement machine learning to help out Lenny, the resident BI "expert". It quickly became apparent that Lenny didn't put the "Intelligence" in Business Intelligence.

Lenny was a long-term contractor who started the BI initiative from the ground-up. His previous work as a front-end developer led to his decision to use PHP for the ETL process. This one-of-a-kind monstrosity made it as unstable as a house of cards in a hurricane and the resultant data warehouse was more like a data cesspool.

"This here is the best piece of software in the whole company," Lenny boasted. "They tell me you're really smart, so you'll figure out how it works on your own. My work is far too important and advanced for me to be bothered with questions!" Lenny told Grady sternly.

Grady, left to fend for himself, spent weeks stumbling through code with very few comments and no existing documentation. He managed to deduce the main workflow for the ETL and warehouse process and it wasn't pretty. The first part of the ETL process deleted the entire existing data warehouse, allowing for a "fresh start" each day. If an error occurred during the ETL, rather than fail gracefully, the whole process crashed without restoring the data warehouse that was wiped out.

Grady found that the morning ETL run failed more often than not. Since Lenny never bothered to stroll in until 10 AM, the people that depended on data warehouse reports loudly complained to Grady. Having no clue how to fix it, he would tell them to be patient. Lenny would saunter in and start berating him "Seriously? Why haven't you figured out how to fix this yet?!" Lenny would spend an hour doing damage control, then disappear for a 90 minute lunch break.

One day, an email arrived informing everyone that Lenny was no longer with the company after exercising an obscure opt-out clause in his contract. Grady suddenly became the senior-most BI developer and inherited Lenny's trash pile. Determined to find the cause of the errors, he dug into parts of the code Lenny strictly forbade him to enter. Hoping to find any semblance of logging that might help, he scoured for hours.

Grady finally started seeing commands called "WritetoSkype". It sounded absurd, but it almost seemed like Lenny was logging to a Skype channel during the ETL run. Grady created a Skype account and subscribed to LennysETLLogging. All he found there was a bunch of dancing penguin emoticons, written one at a time.

Grady scrolled and scrolled and scrolled some more as thousands of dancing penguins written during the day's run performed for him. He finally reached the bottom and found an emoticon of a squirrel eating an acorn. Looking back at the code, WritetoSkype sent (dancingpenguin) when a step succeeded and (heidy) when a step failed. It was far from useful logging, but Grady now had a clear mission - Exterminate all the squirrels.