Is it possible to have a Kusto where statement only if some other condition is met?

I want to write a Kusto function with an optional argument. If the argument is not provided, I don’t want to do a ‘where’ statement. Is that possible?

let f = (a:string = "default") {
    table1
    | where region = a // only do this search if a != default
   
};
f()

>Solution :

you can use the logical or operator:

let f = (a:string = "default") {
    table1
    | where a == 'default' or region == a
};
f()