Module comonad_helpers 

Helper functions demonstrating practical applications of Comonad operations.

This module provides position-aware helper functions that compute structural metadata at every position in a pattern:

• depth_at(): Decorate each position with its depth (maximum nesting level)
• size_at(): Decorate each position with its subtree size (total node count)
• indices_at(): Decorate each position with its path from root (sequence of indices)

These helpers demonstrate how extend enables natural expression of context-aware computation, where functions have access to the full subpattern at each position.