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26. Python Runtime Services

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:

`sys` |  | Access system-specific parameters and functions.
`__builtin__` |  | The module that provides the built-in namespace.
`__main__` |  | The environment where the top-level script is run.
`warnings` |  | Issue warning messages and control their disposition.
`contextlib` |  | Utilities for `with`-statement contexts.
`atexit` |  | Register and execute cleanup functions.
`traceback` |  | Print or retrieve a stack traceback.
`__future__` |  | Future statement definitions
`gc` |  | Interface to the cycle-detecting garbage collector.
`inspect` |  | Extract information and source code from live objects.
`site` |  | A standard way to reference site-specific modules.
`user` |  | A standard way to reference user-specific modules.
`fpectl` |  | Provide control for floating point exception handling.