from typing import TypeVar, List, Iterable, Any, Callable

_T = TypeVar('_T')

def cmp_lt(x, y) -> bool: ...
def heappush(heap: List[_T], item: _T) -> None: ...
def heappop(heap: List[_T]) -> _T:
    raise IndexError()  # if heap is empty
def heappushpop(heap: List[_T], item: _T) -> _T: ...
def heapify(x: List[_T]) -> None: ...
def heapreplace(heap: List[_T], item: _T) -> _T:
    raise IndexError()  # if heap is empty
def merge(*iterables: Iterable[_T]) -> Iterable[_T]: ...
def nlargest(n: int, iterable: Iterable[_T]) -> List[_T]: ...
def nsmallest(n: int, iterable: Iterable[_T]) -> List[_T]: ...