python-shell-completion-setup-code

python-shell-completion-setup-code is a variable defined in `python.el'.
Its value is

"try:\n    import __builtin__\nexcept ImportError:\n    # Python 3\n    import builtins as __builtin__\ntry:\n    import readline, rlcompleter\nexcept:\n    def __PYTHON_EL_get_completions(text):\n        return []\nelse:\n    def __PYTHON_EL_get_completions(text):\n        builtins = dir(__builtin__)\n        completions = []\n        try:\n            splits = text.split()\n            is_module = splits and splits[0] in ('from', 'import')\n            is_ipython = ('__IPYTHON__' in builtins or\n                          '__IPYTHON__active' in builtins)\n            if is_module:\n                from IPython.core.completerlib import module_completion\n                completions = module_completion(text.strip())\n            elif is_ipython and '__IP' in builtins:\n                completions = __IP.complete(text)\n            elif is_ipython and 'get_ipython' in builtins:\n                completions = get_ipython().Completer.all_completions(text)\n            else:\n                i = 0\n                while True:\n                    res = readline.get_completer()(text, i)\n                    if not res:\n                        break\n                    i += 1\n                    completions.append(res)\n        except:\n            pass\n        return completions"

Documentation:
Code used to setup completion in inferior Python processes.

You can customize this variable.