Function strictly_left

pub fn strictly_left<T, U>(
    left: T,
    right: U,
) -> BBStrictlyLeft<T, U::Expression>
where
    T: Expression,
    <T as Expression>::SqlType: SqlType,
    U: AsExpression<T::SqlType>,

The << operator returns TRUE if the bounding box of geometry A is strictly to the left of the bounding box of geometry B.