नया क्या है Python 3.9 में अपेक्षित

d1 = {'one': 1}
d2 = {'two': 2}
#     ,..
d1.update(d2)
# ...  . 
united_dict = d1.copy()
united_dict.update(d2)

united_dict = {**d1, **d2}

from collections import ChainMap
d1 = {'one': 1}
d2 = {'two': 2}
united_dict = ChainMap(d1, d2)

# 
from typing import List
List[str]
# 
list[int]

# 
from typing import OrderedDict
OrderedDict[str, int]
# 
from collections import OrderedDict
OrderedDict[str, int]

def removeprefix(self: str, prefix: str, /) -> str:
    if self.startswith(prefix):
        return self[len(prefix):]
    else:
        return self[:]

	'foobar'.lstrip(('foo',))

def a(func):
	def wrapper():
		print('a')
		func()
	return wrapper
	
def b(func):
	def wrapper():
		print('b')
		func()
	return wrapper
	
decorators = [a, b]

@decorators[0] #   3.8        
def some_func():
	print('original')
	
some_func()
>> a
>> original

import ast
parsed = ast.parse('import pprint; pprint.pprint({"one":1, "two":2})')
unparsed_str = ast.unparse(parsed)
print(unparsed_str)
>> import pprint
>> pprint.pprint({'one': 1, 'two': 2})
exec(unparsed_str)
>> {'one': 1, 'two': 2}

from functools import TopologicalSorter
graph = graph = {8: [3, 7], 11: [5, 7], 2: [11], 9: [8, 11], 10: [3, 11]}
t_sorter = TopologicalSorter(graph)
t_sorted_list = list(t_sorted_list.static_order()) #  ,    ,     static_order.
>> [3, 7, 5, 8, 11, 2, 9, 10]