28. Python Runtime Services
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The modules described in this chapter provide a wide range of services
related to the Python interpreter and its interaction with its
environment.  Here’s an overview:

* 28.1. "sys" — System-specific parameters and functions

* 28.2. "sysconfig" — Provide access to Python’s configuration
  information

  * 28.2.1. Configuration variables

  * 28.2.2. Installation paths

  * 28.2.3. Other functions

* 28.3. "__builtin__" — Built-in objects

* 28.4. "future_builtins" — Python 3 builtins

* 28.5. "__main__" — Top-level script environment

* 28.6. "warnings" — Warning control

  * 28.6.1. Warning Categories

  * 28.6.2. The Warnings Filter

    * 28.6.2.1. Default Warning Filters

  * 28.6.3. Temporarily Suppressing Warnings

  * 28.6.4. Testing Warnings

  * 28.6.5. Updating Code For New Versions of Python

  * 28.6.6. Available Functions

  * 28.6.7. Available Context Managers

* 28.7. "contextlib" — Utilities for "with"-statement contexts

* 28.8. "abc" — Abstract Base Classes

* 28.9. "atexit" — Exit handlers

  * 28.9.1. "atexit" Example

* 28.10. "traceback" — Print or retrieve a stack traceback

  * 28.10.1. Traceback Examples

* 28.11. "__future__" — Future statement definitions

* 28.12. "gc" — Garbage Collector interface

* 28.13. "inspect" — Inspect live objects

  * 28.13.1. Types and members

  * 28.13.2. Retrieving source code

  * 28.13.3. Classes and functions

  * 28.13.4. The interpreter stack

* 28.14. "site" — Site-specific configuration hook

* 28.15. "user" — User-specific configuration hook

* 28.16. "fpectl" — Floating point exception control

  * 28.16.1. Example

  * 28.16.2. Limitations and other considerations