rust armanriazi error [E0596]: cannot borrow `self.` as mutable, as it is behind a `&` reference

The error message you are encountering, error [E0596]: cannot borrow 'self.' as mutable, as it is behind a '&' reference, typically occurs in Rust when you are trying to mutate a value that is borrowed as immutable. In Rust, borrowing rules ensure that you can't mutate a value while it is borrowed by another reference. To fix this error, you need to ensure that you are not trying to mutate a value that is borrowed as immutable.