In fi, local variables, or temp variables, can be declared within the root section of a contract entry. These variables are perfect for non-state related variables that you need to use on the fly during the execution of your contract. This is done by declaring the variable and type. This type is static and can't be changed.
let <type|struct> <variable name> = <value>;
Value must evaluate to a compatible type. Once defined, these variables can be access via their name: