Split out classes and methods into two separate lists.

    Parameters
    ----------
    folds : list of :class:`FoldScopeHelper`
        The result of :func:`_get_fold_levels`.

    Returns
    -------
    classes, functions: list of :class:`FoldScopeHelper`
        Two separate lists of :class:`FoldScopeHelper` objects. The former
        contains only class definitions while the latter contains only
        function/method definitions.

def _split_classes_and_methods(folds):
    """
    Split out classes and methods into two separate lists.

    Parameters
    ----------
    folds : list of :class:`FoldScopeHelper`
        The result of :func:`_get_fold_levels`.

    Returns
    -------
    classes, functions: list of :class:`FoldScopeHelper`
        Two separate lists of :class:`FoldScopeHelper` objects. The former
        contains only class definitions while the latter contains only
        function/method definitions.
    """
    classes = []
    functions = []
    for fold in folds:
        if fold.def_type == OED.FUNCTION_TOKEN:
            functions.append(fold)
        elif fold.def_type == OED.CLASS_TOKEN:
            classes.append(fold)

    return classes, functions