files + aio
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1d99879eae
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.gitignore
vendored
1
.gitignore
vendored
@ -158,3 +158,4 @@ cython_debug/
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# and can be added to the global gitignore or merged into this file. For a more nuclear
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# option (not recommended) you can uncomment the following to ignore the entire idea folder.
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#.idea/
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tmp/
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211
main.ipynb
211
main.ipynb
@ -34,19 +34,224 @@
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" to load C-like DLLs\n",
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" * https://docs.python.org/3/extending/ \\\n",
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" if you need C\n",
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" * https://docs.python.org/3/whatsnew/ \\\n",
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" there's a lot of important stuff posted there, actually (e.g. `match` keyword)\n",
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" * https://docs.python.org/3/reference/ \\\n",
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" in-depth about python itself\n",
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" * https://docs.python.org/3/reference/datamodel.html \\\n",
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" the most important part from that reference\n",
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"* https://wiki.python.org/moin/FrontPage \\\n",
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" at the moment of writing, haven't read much of it"
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]
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},
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{
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"cell_type": "markdown",
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"id": "5a56ce30-37b4-463f-a446-895198dc0db8",
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"id": "07390193-fdde-4bee-aec4-f5b3227dea06",
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"metadata": {
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"jp-MarkdownHeadingCollapsed": true,
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"tags": []
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},
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"source": [
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"# Working with files"
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"# typing\n",
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"Even a dynamically typed language can sometimes, at least, declare types. Python has built-in support for that via annotations."
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]
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},
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{
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"cell_type": "markdown",
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"id": "c726cf29-f81e-4e52-95f1-128057fe4d0a",
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"metadata": {
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"tags": []
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},
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"source": [
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"# Data model\n",
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"https://docs.python.org/3/reference/datamodel.html"
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]
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},
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{
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"cell_type": "markdown",
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"id": "5a56ce30-37b4-463f-a446-895198dc0db8",
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"metadata": {
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"tags": []
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},
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"source": [
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"# Working with files\n",
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"There are a lot of ways, and directly using `open`+`.write`/`.read` is probably not fit for you task."
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]
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},
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{
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"cell_type": "markdown",
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"id": "daec179e-49a7-441e-95b4-d1b5d2c489fb",
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"metadata": {
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"tags": []
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},
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"source": [
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"## `pathlib.Path`\n",
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"One of the most overlooked python's modules is `pathlib`.\n",
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"Even more rare is the knowledge that `Path` objects have `.open`, `.write_*` and `.read_*` methods."
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]
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},
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{
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"cell_type": "code",
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"execution_count": 9,
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"id": "b25fe82a-f87e-425d-81b4-bf1c0c2baf0f",
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"metadata": {},
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"outputs": [
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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"5\n",
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"6\n",
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"\n"
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]
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}
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],
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"source": [
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"import pathlib\n",
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"tmp = pathlib.Path('tmp/')\n",
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"tmp.mkdir(exist_ok=True)\n",
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"example_txt = tmp / 'example.txt'\n",
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"example_txt.touch(exist_ok=True)\n",
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"example_txt.write_text(f'{2+3}\\n{2*3}\\n')\n",
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"print(example_txt.read_text())"
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]
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},
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{
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"cell_type": "markdown",
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"id": "4e39ce1a-3396-45c9-bcad-19784326c32e",
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"metadata": {
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"tags": []
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},
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"source": [
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"## File(-like) objects\n",
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"Returned by `open(...)` and `pathlib.Path(...).open(...)`."
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]
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},
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{
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"cell_type": "code",
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"execution_count": 12,
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"id": "c59f89f6-d222-4382-8459-dd72c00f746e",
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"metadata": {},
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"outputs": [
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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"5\n",
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"6\n",
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"\n",
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"5\n",
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"\n",
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"6\n",
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"\n"
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]
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}
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],
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"source": [
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"# avoid using `open` outside `with` (`with` better guarantees file's closure)\n",
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"with open(example_txt, 'w') as f:\n",
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" f.write(f'{2+3}\\n{2*3}\\n')\n",
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"with open(example_txt) as f:\n",
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" print(f.read())\n",
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"with open(example_txt) as f:\n",
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" for line in f:\n",
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" print(line)"
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]
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},
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{
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"cell_type": "markdown",
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"id": "6519c846-90fd-4828-9861-3cac9954880f",
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"metadata": {
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"tags": []
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},
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"source": [
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"# asyncio\n",
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"If you do anything with IO, you should probably do it **asynchronously** \\\n",
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"https://docs.python.org/3/library/asyncio.html"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 2,
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"id": "ffc18b3f-f63a-4556-bc24-d3a7d69756ac",
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"metadata": {},
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"outputs": [],
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"source": [
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"import asyncio"
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]
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},
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{
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"cell_type": "markdown",
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"id": "c0fe1271-d784-4c45-9294-795a6b01b785",
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"metadata": {
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"tags": []
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},
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"source": [
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"## Background\n",
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"The most prominent use of async IO is undoubtably anything that has to do with JavaScript (the web programming language). \\\n",
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"Due to \\{1) limitations in performance 2) single-threaded environment (that can't allow any freezes) 3) constantly working with high-latency IO (because internet, client- and server-side) of high frequency (and high (number-wise) loads for servers)\\}, JS kind of has to resort to using an event loop. \\\n",
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"All IO in JS is forced to be async. \\\n",
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"In browsers that is to prevent incompetent or malicious actors from killing your browser (or parts of it). \\\n",
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"In Node that is to prevent obviously unnecessary blocking of code to achieve better performance. \\\n",
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"Ryan Dahl on Node.js: \\\n",
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"https://youtu.be/ztspvPYybIY \\\n",
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"https://youtu.be/jo_B4LTHi3I"
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]
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},
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{
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"cell_type": "markdown",
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"id": "f06ca023-f840-4488-b9b2-cfd302193858",
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"metadata": {
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"tags": []
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},
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"source": [
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"## Level 0: working inside async framework\n",
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"If you've ever worked with `aiohttp` or `discord.py`/`disnake`, you've probably encountered `async`/`await` syntax. \\\n",
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"It may seems like these frameworks just make you put this magic words here and there. \\\n",
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"But there are reasons for both these magic words."
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]
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},
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{
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"cell_type": "markdown",
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"id": "d46018f9-8609-4408-ab97-48dbea0bfd7c",
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"metadata": {
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"tags": []
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},
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"source": [
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"### `async def` -- define an asynchronous function (coroutine)\n",
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"`async` here signals to python that the function might use `await`s inside it. \\\n",
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"Statements *inside* coroutines are guaranteed to happen in sequence with each other"
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]
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},
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{
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"cell_type": "markdown",
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"id": "5205f839-7b22-4144-9e7c-29093b05e2ca",
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"metadata": {
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"tags": []
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},
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"source": [
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"### `await` -- virtually block on a future or on another coroutine and return result\n",
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"While coroutine `await`s, other coroutines can be (and, probably, are) doing their own stuff. \\\n",
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"Any code between `await`s happens sequentially with all the other code, i.e. unlike `threading`, `async` does not mix statements unpredictably. \\\n",
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"You always have the exclusive and direct control of data in code fragments where you don't `await`. \\\n",
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"Expression `(await f(...))` where `f` is defined as `async def f(...): ...` with `return x` evaluates to that `x`. \\\n",
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"Expression `(await future)` where `f` is `asyncio.Future` that has someone call `.set_result(x)` evaluates to that `x`. \\"
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]
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},
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{
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"cell_type": "markdown",
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"id": "f9cf426c-94fa-4907-b182-a759d0934080",
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"metadata": {},
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"source": [
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"### `async with` -- asynchronous context management\n",
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"Same as `with`, but `async def __aenter__`/`async def __aexit__` instead of `def __enter__`/`def __exit__`."
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]
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},
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{
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"cell_type": "markdown",
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"id": "21f08324-0b14-4b35-bc6e-7a7329520ed9",
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"metadata": {},
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"source": [
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"## Level 1: using high-level APIs"
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]
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},
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{
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