如何将嵌套的字典键和值展开到它们的类型和变量的平面列表中？

def flatten_dict(dictionary, parent_key='', sep='_'):
    items = []
    for key, value in dictionary.items():
        new_key = parent_key + sep + key if parent_key else key
        if isinstance(value, dict):
            items.extend(flatten_dict(value, new_key, sep=sep).items())
        else:
            items.append((new_key, value))
    return dict(items)

nested_dict = {
    'a': 1,
    'b': {
        'c': 2,
        'd': {
            'e': 3
        }
    }
}

flattened_dict = flatten_dict(nested_dict)
print(flattened_dict)

{
    'a': 1,
    'b_c': 2,
    'b_d_e': 3
}