[docs] [issue31139] Improve tracemalloc demo code in docs

[Louie Lu]

New submission from Louie Lu:

Current tutorial of tracemalloc:
https://docs.python.org/3/library/tracemalloc.html

Current doc using a un-reproducible output, that will confuse the reader. Propose to use the test code `allocate_bytes` to control the memory usage output, provide more meaningful output to reader.

----------
assignee: docs at python
components: Documentation
messages: 299892
nosy: docs at python, haypo, louielu
priority: normal
severity: normal
status: open
title: Improve tracemalloc demo code in docs
type: enhancement
versions: Python 3.7

_______________________________________
Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue31139>
_______________________________________