rust/src/doc/trpl/glossary.md

% Glossary

Not every Rustacean has a background in systems programming, nor in computer
science, so we've added explanations of terms that might be unfamiliar.

### Arity

Arity refers to the number of arguments a function or operation takes.

```rust
let x = (2, 3);
let y = (4, 6);
let z = (8, 2, 6);
```

In the example above `x` and `y` have arity 2. `z` has arity 3.