from collections import defaultdict
from typing import Iterator, List, DefaultDict, Optional

section: DefaultDict[str, List[str]] = defaultdict(list)
curr_section: Optional[str] = None

section[curr_section].strip()

def fib(n: int) -> Iterator[int]:
    a, b = 0, 1
    while a < n:
        yield a
        a, b = b, a + b


fib(10)
fib("10")