// ## Unique, mutable references
//@ There is a second way to borrow something, a second kind of reference: The *mutable reference*. This is a reference that comes with the promise
// ## Unique, mutable references
//@ There is a second way to borrow something, a second kind of reference: The *mutable reference*. This is a reference that comes with the promise
//@ Because there cannot be another reference to the same data, we could also call it a *unique* reference, but that is not their official name.
//@ As an example, consider a function which increments every element of a vector by 1.
//@ Because there cannot be another reference to the same data, we could also call it a *unique* reference, but that is not their official name.
//@ As an example, consider a function which increments every element of a vector by 1.