Qt.py is a single-file Python compatibility shim that provides a unified API across PySide6, PyQt6, PySide2, and PyQt5 Qt bindings. It exports a curated set of common member classes and functions, ensuring that code written with `from Qt import ...` works identically on any supported binding. The library handles disparities in module structure (e.g., QAction location), different signal/slot syntax, and missing utilities like `loadUi` by implementing its own `QUiLoader`-based fallback. It also includes a command-line tool for converting PySide2-compiled .ui files, and supports per-import configuration via environment variables and `QtSiteConfig.py`. While primarily a library, it has CLI entry points and extensive test infrastructure.