如何将嵌套列表作为新列添加到现有pandas数据框中

import pandas as pd

data = {'A': [1, 2, 3], 'B': [[4, 5], [6, 7], [8, 9]]}
df = pd.DataFrame(data)

def flatten_list(lst):
    return [item for sublist in lst for item in sublist]

df['C'] = df['B'].apply(flatten_list)

import pandas as pd

data = {'A': [1, 2, 3], 'B': [[4, 5], [6, 7], [8, 9]]}
df = pd.DataFrame(data)

def flatten_list(lst):
    return [item for sublist in lst for item in sublist]

df['C'] = df['B'].apply(flatten_list)