Find maximum follow depth using recursion

You are given a directed **follows** relationship representing a social graph: - Each record `(follower_id, followee_id)` means `follower_id` follows `followee_id`. - Treat this as a directed graph. ### Task Implement a function that, given: - a list of follow edges `follows = [(follower_id, followee_id), ...]` - a starting user `start_id` returns the **maximum number of follow “layers”** reachable from `start_id` by repeatedly following the next user. Formally, compute the length of the longest directed path starting at `start_id`: - Layer 1: users directly followed by `start_id` - Layer 2: users followed by those users - … Return the maximum layer count reachable. ### Requirements / edge cases - Use recursion (you may add memoization). - Handle cycles (e.g., A→B→C→A) without infinite recursion. - If `start_id` follows nobody, return `0`. ### Example If edges are: `1→2, 2→3, 3→4`, then `max_depth(1) = 3` (layers: {2}, {3}, {4}). If edges are: `1→2, 2→1`, then `max_depth(1) = 1` (cycle; do not loop forever).