Method sort

datafusion/expr/src/expr.rs:1951–1953

Create a sort configuration from an existing expression. ``` # use datafusion_expr::col; let sort_expr = col("foo").sort(true, true); // SORT ASC NULLS_FIRST ```

(self, asc: bool, nulls_first: bool)

    /// let sort_expr = col("foo").sort(true, true); // SORT ASC NULLS_FIRST
    /// ```
    pub fn sort(self, asc: bool, nulls_first: bool) -> Sort {
        Sort::new(self, asc, nulls_first)
    }

    /// Return `IsTrue(Box(self))`
    pub fn is_true(self) -> Expr {