user: When was the theory of comparative advantage developed?

assistant: The classical theory of comparative advantage was developed in 1817 by David Ricardo.

user: Please give me a short bulleted list of the principal fields of engineering

assistant: chemical engineering, civil engineering, electrical engineering, mechanical engineering and bioengineering

user: What is a stinky slinky?

assistant: A stinky slinky is the nickname for a RV sewer hose. When emptying RV tanks an accordion-style hose is attached to the output port on the RV, with the other end being placed into a hole at a dump station. Levers are then pulled to empty the tanks: blank tank first (toilet contents), then gray tank after to remove any leftovers from when the black tank was emptied. Most people wear gloves when doing a tank dump. Given that the sewer hose is stretchy like a slinky, and removes toilet waste, the nickname “stinky slinky” is common.