don't rmtree() if directory doesn't exist

Drop test for tracing and inline coroutine creation

16: Warn for specific thread module methods r=ltratt a=nanjekyejoannah Dont merge until python#13 and python#14 are merged, some helper code cuts across. This replaces python#15 Threading module Notes Python 2: ``` >>> from thread import get_ident >>> from threading import get_ident Traceback (most recent call last): File "<stdin>", line 1, in <module> ImportError: cannot import name get_ident >>> import threading >>> from threading import _get_ident >>> ``` Python 3: ``` >>> from threading import get_ident >>> from thread import get_ident Traceback (most recent call last): File "<stdin>", line 1, in <module> ModuleNotFoundError: No module named 'thread' > ``` **Note:** There is no neutral way of porting Co-authored-by: Joannah Nanjekye <jnanjekye@python.org>

API documentation. Closes python#16

Lazy globals