Pyupgrade to Python 3.9 (#4718)

* Pyupgrade to Python 3.9

* updating DIRECTORY.md

Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>

blockchain/chinese_remainder_theorem.py

@@ -11,11 +11,11 @@ Algorithm :
 1. Use extended euclid algorithm to find x,y such that a*x + b*y = 1
 2. Take n = ra*by + rb*ax
 """
-from typing import Tuple
+from __future__ import annotations
 
 
 # Extended Euclid
-def extended_euclid(a: int, b: int) -> Tuple[int, int]:
+def extended_euclid(a: int, b: int) -> tuple[int, int]:
     """
     >>> extended_euclid(10, 6)
     (-1, 2)

blockchain/diophantine_equation.py

@@ -1,7 +1,7 @@
-from typing import Tuple
+from __future__ import annotations
 
 
-def diophantine(a: int, b: int, c: int) -> Tuple[float, float]:
+def diophantine(a: int, b: int, c: int) -> tuple[float, float]:
     """
     Diophantine Equation : Given integers a,b,c ( at least one of a and b != 0), the
     diophantine equation a*x + b*y = c has a solution (where x and y are integers)
@@ -95,7 +95,7 @@ def greatest_common_divisor(a: int, b: int) -> int:
     return b
 
 
-def extended_gcd(a: int, b: int) -> Tuple[int, int, int]:
+def extended_gcd(a: int, b: int) -> tuple[int, int, int]:
     """
     Extended Euclid's Algorithm : If d divides a and b and d = a*x + b*y for integers
     x and y, then d = gcd(a,b)

blockchain/modular_division.py

@@ -1,4 +1,4 @@
-from typing import Tuple
+from __future__ import annotations
 
 
 def modular_division(a: int, b: int, n: int) -> int:
@@ -73,7 +73,7 @@ def modular_division2(a: int, b: int, n: int) -> int:
     return x
 
 
-def extended_gcd(a: int, b: int) -> Tuple[int, int, int]:
+def extended_gcd(a: int, b: int) -> tuple[int, int, int]:
     """
     Extended Euclid's Algorithm : If d divides a and b and d = a*x + b*y for integers x
     and y, then d = gcd(a,b)
@@ -101,7 +101,7 @@ def extended_gcd(a: int, b: int) -> Tuple[int, int, int]:
     return (d, x, y)
 
 
-def extended_euclid(a: int, b: int) -> Tuple[int, int]:
+def extended_euclid(a: int, b: int) -> tuple[int, int]:
     """
     Extended Euclid
     >>> extended_euclid(10, 6)