```python
def flip_one(pair: list) -> list:
    """Return a new list with the two members of the pair swapped."""
    if len(pair) != 2:
        raise ValueError("pair must contain exactly two elements")
    return [pair[1], pair[0]]


def flip_all(pairs: list) -> list:
    """Return a new list with each pair in the input list flipped."""
    return [flip_one(pair) for pair in pairs]
```