Iterative DFS with Explicit Stack

Concepts: pyIterativeDFS, pyTopoSort, pyKahns

Python's default recursion limit is 1000 frames. A production DAG with 5,000 tables will crash recursive DFS. A graph representing a large schema with deep nesting will crash it. The iterative DFS pattern replaces the call stack with an explicit stack, removing the depth limit and giving you control over traversal order. Every recursive DFS can be mechanically converted to iterative. The explicit stack mirrors what the call stack was doing implicitly. Recursive vs Iterative DFS: The Conversion The reversal of neighbors is the subtle detail. In recursive DFS, the first neighbor in the adjacency list is the first one processed (because it is the first recursive call). In iterative DFS, you push all neighbors, so the LAST pushed is the FIRST processed (LIFO). To match recursive pre-order trav