In the 1930s, while Turing was developing what are now called ‘Turing machines’ as a model for computation, Church and his student Kleene were developing a different model, called the ‘lambda calculus’ [29, 63]. While a Turing machine can be seen as an idealized, simplified model of computer hardware, the lambda calculus is more like a simple model of software.

I gotcha now, ya little twerp.

First spotted at the top of ships' masts (where they were considered a good omen), Saint Elmo's fires are typically seen around tall metal grounded objects, such as lightning rods, aircraft wings, and chimney tops.

I am afraid lest I revealed too much.