Use curly braces ("{" and "}") to open and close a code block. They create a separate scope for previously non-existing variables defined within them, which begins with "{" and ends with "}". Note that if a variable existed in an outer scope, it cannot be created in the inner scope.
Note that if-true, run-query, start-loop and read-line statements contain implicit code blocks, meaning the code between them and the accompanying end-statement is within implicit "{" and "}".
Examples
The following code will first print out "outside" and then "inside" twice, illustrating the fact that variable "s1" is defined only in the outer scope once. Variable "s2" exists only in inner scope: