Input: Article: On March 30, 2015, it was announced that Beyoncé is a co-owner, with various other music artists, in the music streaming service Tidal. The service specialises in lossless audio and high definition music videos. Beyoncé's husband Jay Z acquired the parent company of Tidal, Aspiro, in the first quarter of 2015. Including Beyoncé and Jay-Z, sixteen artist stakeholders (such as Kanye West, Rihanna, Madonna, Chris Martin, Nicki Minaj and more) co-own Tidal, with the majority owning a 3% equity stake. The idea of having an all artist owned streaming service was created by those involved to adapt to the increased demand for streaming within the current music industry, and to rival other streaming services such as Spotify, which have been criticised for their low payout of royalties. "The challenge is to get everyone to respect music again, to recognize its value", stated Jay-Z on the release of Tidal.

Now answer this question: When was it discovered Beyonce was a co-owner of the music service, Tidal?

Output: March 30, 2015

Input: Article: In the late 19th century, the most influential theorists were William James (1842–1910) and Carl Lange (1834–1900). James was an American psychologist and philosopher who wrote about educational psychology, psychology of religious experience/mysticism, and the philosophy of pragmatism. Lange was a Danish physician and psychologist. Working independently, they developed the James–Lange theory, a hypothesis on the origin and nature of emotions. The theory states that within human beings, as a response to experiences in the world, the autonomic nervous system creates physiological events such as muscular tension, a rise in heart rate, perspiration, and dryness of the mouth. Emotions, then, are feelings which come about as a result of these physiological changes, rather than being their cause.

Now answer this question: In what year did Lange die?

Output: 1900

Input: Article: A few lines of the Paris Métro in France operate on a four-rail power scheme because they run on rubber tyres which run on a pair of narrow roadways made of steel and, in some places, concrete. Since the tyres do not conduct the return current, the two guide rails provided outside the running 'roadways' double up as conductor rails, so at least electrically it is a four-rail scheme. One of the guide rails is bonded to the return conventional running rails situated inside the roadway so a single polarity supply is required. The trains are designed to operate from either polarity of supply, because some lines use reversing loops at one end, causing the train to be reversed during every complete journey. The loop was originally provided to save the original steam locomotives having to 'run around' the rest of the train saving much time. Today, the driver does not have to change ends at termini provided with such a loop, but the time saving is not so significant as it takes almost as long to drive round the loop as it does to change ends. Many of the original loops have been lost as lines were extended.

Now answer this question: What is required in order for the guide rails to operate properly?

Output:
a single polarity supply