Write down a typing rule $($call it WHILE$\_$STMT$)$ for the 'while' loop statement 'while e do s$\text{'},$ where $\text{'}$e$\text{'}$ must evaluate to a boolean, and $\text{'}$s$\text{'}$ can be either a single statement or a block of statements. Define and clarify that in our type system, both individual statements and blocks of statements are categorized under the type $\text{'}$stmt$".$