You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: invariants-typestates-basic-1-2.rs
    path of file: ./repos/prusti-dev/prusti-tests/tests_old/verify/fail/erdinm
    
    the code of the file until where you have to start completion: use prusti_contracts::*;

use std::marker::PhantomData;

struct Neg;
struct Pos
    
    fn to_sign(&mut self) {
        if self.i <= -1 {
            self.i = -1;
        } else if self.i >= 1 {
            self.i = 1;
        }
    }