Pythonでイテレータの先読みやPushBackをするには ref: https://qiita.com/kurogelee/items/654e6083d37c4259d42d

peek.py

from typing import TypeVar, Iterable, Generator, List
from more_itertools import peekable

T = TypeVar("T")
Gen = Generator[T, None, None]


def partition(items: Iterable[T]) -> Gen[List[T]]:
    items = peekable(items)
    result = []
    sentinel = object()
    for item in items:
        next_item = items.peek(sentinel)
        result.append(item)
        if item != next_item:
            yield result
            result = []


parted = partition([1, 1, 2, 4, 4, 4, 1, 2, 2, 4, 4, 5, 5])
print(list(parted))