def _flatten_dict(params: MutableMapping[Any, Any], delimiter: str = "/", parent_key: str = "") -> Dict[str, Any]:
    """Flatten hierarchical dict, e.g. ``{'a': {'b': 'c'}} -> {'a/b': 'c'}``.

    Args:
        params: Dictionary containing the hyperparameters
        delimiter: Delimiter to express the hierarchy. Defaults to ``'/'``.

    Returns:
        Flattened dict.

    Examples:
        >>> _flatten_dict({'a': {'b': 'c'}})
        {'a/b': 'c'}
        >>> _flatten_dict({'a': {'b': 123}})
        {'a/b': 123}
        >>> _flatten_dict({5: {'a': 123}})
        {'5/a': 123}
        >>> _flatten_dict({"dl": [{"a": 1, "c": 3}, {"b": 2, "d": 5}], "l": [1, 2, 3, 4]})
        {'dl/0/a': 1, 'dl/0/c': 3, 'dl/1/b': 2, 'dl/1/d': 5, 'l': [1, 2, 3, 4]}

    """
    result: Dict[str, Any] = {}
    for k, v in params.items():
        new_key = parent_key + delimiter + str(k) if parent_key else str(k)
        if is_dataclass(v):
            v = asdict(v)
        elif isinstance(v, Namespace):
            v = vars(v)

        if isinstance(v, MutableMapping):
            result = {**result, **_flatten_dict(v, parent_key=new_key, delimiter=delimiter)}
        # Also handle the case where v is a list of dictionaries
        elif isinstance(v, list) and all(isinstance(item, MutableMapping) for item in v):
            for i, item in enumerate(v):
                result = {**result, **_flatten_dict(item, parent_key=f"{new_key}/{i}", delimiter=delimiter)}
        else:
            result[new_key] = v
    return result