RcRefCellT
RcRefCellT is a Rust programming language construct that combines reference counting with interior mutability. It is defined in the `std::rc` module and provides a way to have multiple immutable references to a value while still being able to modify that value.
The `Rc` part stands for "Reference Counted." It allows multiple owners of the same data. When the
The `RefCell` part provides "interior mutability." Normally, Rust enforces strict borrowing rules: you can have either
When you try to borrow from a `RefCell`, it will either give you a mutable reference (`borrow_mut`)