Implements a thread-safe Singleton metaclass. Used by BotCache and BotState to ensure a single shared instance across the application. The pattern is clean, minimal, and can be extracted into any Python project requiring a singleton.

Provides a `file` class that wraps common file operations (append, remove, random line selection, save list) with logging. It is self-contained, parameterized, and solves the recurring problem of managing plaintext configuration and state files. Easily reusable in any project that needs simple file-based persistence.

Implements save/load of bot state (counters, blocked actions, request counts) using pickle serialization. The module is isolated, with clear methods for checkpointing and restoring. This pattern is reusable in any long-running automation or batch process that needs to resume after interruption.

Provides a time-to-live (TTL) cache for user info, usernames, and follow relationships. Uses a dictionary with expiration timestamps and a cleanup method. The implementation is self-contained and demonstrates a simple but effective caching strategy that can be extracted for any application needing short-lived data caching.