from __future__ import annotations

from typing import *

from typing_extensions import *

PAD_INDEX = Union[

Tuple[Union[int, None], Union[int, None], int],

Tuple[Union[int, None], Union[int, None]],

Tuple[Union[int, None]],

int,

]

"""Filter pad index.

- 3-element tuple = (chain, filter, pad)]

- 2-element tuple = (filter, pad)

- 1-element tuple = (pad,)

- int = pad

A None item indicates not specified and

usually means to assign first available

"""

PAD_PAIR = Union[

Tuple[PAD_INDEX, PAD_INDEX],

Tuple[Union[PAD_INDEX, List[PAD_INDEX]], None],

Tuple[None, PAD_INDEX],

]

"""Specifies a filter pad linkage or labeling

A tuple pair of input pad and output pad.

- Set input or output pad is ``None`` to define a pad label

- If input label is an input stream specifier (e.g., 0:v or 1:a:0) and connects

to multiple filter inputs, specify with a list the input pad indices.

"""

JOIN_HOW = Literal["chainable", "per_chain", "all", "auto"]