import numpy as np

class Index:
    def add(self, x: np.ndarray) -> None: ...
    def search(self, x: np.ndarray, k: int) -> tuple[np.ndarray, np.ndarray]: ...
    def remove_ids(self, x: np.ndarray) -> None: ...
    def add_with_ids(self, x: np.ndarray, xids: np.ndarray) -> None: ...
    ntotal: int

class IndexIDMap(Index):
    def __init__(self, base_index: Index) -> None: ...
    def add_with_ids(self, x: np.ndarray, xids: np.ndarray) -> None: ...
    def reconstruct(self, key: int) -> np.ndarray: ...

class IndexFlatL2(Index):
    def __init__(self, d: int) -> None: ...

def read_index(filename: str) -> Index: ...
def write_index(index: Index, filename: str | None) -> None: ...
def normalize_L2(x: np.ndarray) -> None: ...