snippets on python's coroutines and asyncio library.

async.py

import asyncio
import time

# Hello world async/await
async def hello():
    print("Hello")
    await asynio.sleep(2)
    print("World!")
  
asyncio.run(hello())


# cooperative multitasking using asyncio.gather

async def chill(label: str, n: int):
    print(f"{label}: Chilling for {n} seconds")
    await asyncio.sleep(n)
    print(f"Done chilling for {label}")



async def gather():
    T = asyncio.gather(chill("A", 2), chill("B", 5), chill("C", 3))
    starttime = time.perf_counter()
    await T
    endtime = time.perf_counter()
    print(f"Task finished in {endtime - starttime}")

asyncio.run(gather()) 

""" Sample output:

A: Chilling for 2 seconds
B: Chilling for 5 seconds
C: Chilling for 3 seconds
Done chilling for A
Done chilling for C
Done chilling for B
Task finished in 5.004022927998449
"""

async def task_create():
    task1 = asyncio.create_task(chill("A", 2))
    task2 = asyncio.create_task(chill("B", 5))
    task3 = asyncio.create_task(chill("C", 3))

    starttime = time.perf_counter()
    await task1
    await task2
    await task3
    endtime = time.perf_counter()
    print(f"Task finished in {endtime - starttime}")

asyncio.run(task_create())

""" Sample Output:
A: Chilling for 2 seconds
B: Chilling for 5 seconds
C: Chilling for 3 seconds
Done chilling for A
Done chilling for C
Done chilling for B
Task finished in 5.003572109999368
"""