Tuples
A tuple type is written as (t, u) (or (t, u, v), etc.)
The functions a, b, c, etc., access elements of the tuple.
A tuple is created by calling new. See "new" functions for info about its syntax.
You can destructure a tuple by writing multiple local names separated by commas.
All features of locals work inside destructuring, such as type annotations, mut, or _.
Even destructuring works inside destructuring.
Parameters can destructure tuples too. Since parameter types are required, each part of the destructure needs a type.