def METHOD_NAME(
    observables_results: list[tuple[complex, dict]],
    observables: ListOrDict[BaseOperator | PauliSumOp],
) -> ListOrDict[tuple[complex, dict[str, Any]]]:
    """
    Prepares a list of tuples of eigenvalues and metadata tuples from
    ``observables_results`` and ``observables``.
    Args:
        observables_results: A list of tuples (mean, metadata).
        observables: A list or a dictionary of operators whose expectation values are to be
            calculated.
    Returns:
        A list or a dictionary of tuples (mean, metadata).
    """
    if isinstance(observables, list):
        # by construction, all None values will be overwritten
        observables_eigenvalues: ListOrDict[tuple[complex, complex]] = [None] * len(observables)
        key_value_iterator = enumerate(observables_results)
    else:
        observables_eigenvalues = {}
        key_value_iterator = zip(observables.keys(), observables_results)
    for key, value in key_value_iterator:
        observables_eigenvalues[key] = value
    return observables_eigenvalues