mypy-guide-stubs-1.py

#test.py

cache = {}

def fibonacci(n):
    """Fibonacci series implementation"""
    if n <= 1:
        return 1
    
    if n in cache:
        return cache[n]
    
    result = fibonacci(n-1) + fibonacci(n-2)
    cache[n] = result
    return result

for i in range(6):
    print(fibonacci(i))

# Output:
# 1
# 1
# 2
# 3
# 5
# 8

mypy-guide-stubs-2.pyi

# test.pyi
from typing import Dict

cache: Dict[int, int]
def fibonacci(n: int) -> int: ...