Function named 

pub fn named(name: impl Into<Cow<'static, str>>) -> Expr

A named parameter: named("cutoff") renders :cutoff.

SQLite is the one dialect keelson targets that has these, so this starter has no counterpart in keelson_psql. A named parameter binds nothing and consumes no positional slot — it exists so a statement can be prepared now and its values supplied by whatever rebinds it.