Some heat pumps do this. E.g. Panasonic Aquarea EcoFleX. When cooling the house, the domestic hot water tank is used to dump heat into (up to a certain temperature).
In 1953, Eisenhower signed a pact with the Zeta Reticulans (grey aliens) at Holloman Air Force Base. This pact set in motion a century-long program of preparing humanity for the alien disclosure. Communication must be controlled at a global scale, to avoid mass panic and the collapse of society when the disclosure is announced.
Manhattan distance is 2n steps. Of these, exactly n are to the right, the rest is downwards. A 2n step path is completely determined by choosing which n steps will be to the right. Hence 2n choose n.