As an OCaml developer, I need to understand how to create and modify mutable integer variables. Explain how OCaml handles mutable data using `Refs`, and provide the exact OCaml code to initialize a ref with the value 5 and then update its value to 10.
Navigate to the 'Table of Contents' if not already there. From the Table of Contents, click on 'Imperative Programming' under 'Language Concepts'. On the 'Imperative Programming' page, click on 'Mutable Record and Object Fields and Ref Cells' under 'Primitive Mutable Data'. Read the explanation about 'Ref cells' to understand how mutable variables are handled. Identify the OCaml code snippet for initializing a ref and updating its value. State the explanation and the exact OCaml code for initializing a ref with 5 and updating it to 10.
The explanation clearly states that `Refs` are used for mutable variables in OCaml, acting as containers for a single mutable value. The provided OCaml code for initializing a ref with the value 5 is `let x = ref 5;;`. The provided OCaml code for updating the ref's value to 10 is `x := 10;;`.