1error[E0596]: cannot borrow `v` as mutable, as it is not declared as mutable 2 --> $DIR/writing-to-immutable-vec.rs:3:5 3 | 4LL | let v: Vec<isize> = vec![1, 2, 3]; 5 | - help: consider changing this to be mutable: `mut v` 6LL | v[1] = 4; 7 | ^ cannot borrow as mutable 8 9error: aborting due to previous error 10 11For more information about this error, try `rustc --explain E0596`. 12