Implement the N-Queens Algorithm

The N-Queens problem asks you to place N queens on an N×N chessboard so that no two queens attack each other (no two share a row, column, or diagonal). For example, if there is a 4x4 board, one valid arrangement is: ```md [1, 3, 0, 2] ``` That means that in row 0, the queen is placed in column 1; in row 1, the queen is placed in column 3; in row 2, the queen is placed in column 0; and in row 3, the queen is placed in column 2. Visually, this arrangement looks like: ```md . Q . . . . . Q Q . . . . . Q . ``` Where `Q` represents a queen and `.` represents an empty square. In this lab, you will implement the N-Queens problem solver using the depth-first search approach. **Objective**: Fulfill the user stories below and get all the tests to pass to complete the lab. **User Stories:** 1. You should have a function named `dfs_n_queens`. 2. The function should accept exactly one argument: an integer `n`. 3. If `n` is less than `1`, the function should return an empty list (`[]`). 4. The function should return a list of solutions; each solution is itself a list of length `n`, where the element at index `i` is the column index (0-based) of the queen in row `i`.