Method is_null

datafusion/expr/src/expr.rs:1936–1938

Return `IsNull(Box(self))

(self)

    /// Return `IsNull(Box(self))
    pub fn is_null(self) -> Expr {
        Expr::IsNull(Box::new(self))
    }

    /// Return `IsNotNull(Box(self))
    pub fn is_not_null(self) -> Expr {