To change Value<'a> to Value<'v> in the return type, you need to ensure that:

1. The struct has a lifetime parameter 'v: The struct implementing this method must be defined with a lifetime 'v, e.g., struct MyStruct<'v> { ... }.

2. 'v outlives 'a: The lifetime 'v of the Values must outlive the reference lifetime 'a (i.e., 'v: 'a). This ensures the Values remain valid for the duration of the returned slice.

Here's the corrected signature if your struct is MyStruct<'v>:

impl<'v> MyStruct<'v> {
    pub fn peek_frame<'a>(&'a self) -> Option<&'a [Value<'v>]>
    where
        'v: 'a, // Ensure 'v outlives 'a
    {
        // ... implementation ...
    }
}

Key Points:

• Struct Lifetime: The struct must carry the 'v lifetime (e.g., MyStruct<'v>).
• Lifetime Relationship: Add where 'v: 'a to enforce that 'v outlives the reference's lifetime 'a.
• Validity: The Values in the slice must be borrowed from data owned by the struct (with lifetime 'v), not from the &'a self reference.

If these conditions aren’t met, the change will not compile.