如何修改此对象的结构，以日期为关键对象，并将同一日期内完成的所有活动与其配对

# 原始对象
activities = [
    {"date": "2022-01-01", "activity": "A"},
    {"date": "2022-01-01", "activity": "B"},
    {"date": "2022-01-02", "activity": "C"},
    {"date": "2022-01-03", "activity": "D"},
    {"date": "2022-01-03", "activity": "E"}
]

# 新对象
modified_obj = {}

# 修改对象结构
for activity in activities:
    date = activity["date"]
    if date not in modified_obj:
        modified_obj[date] = [activity["activity"]]
    else:
        modified_obj[date].append(activity["activity"])

# 打印修改后的对象
for date, activities in modified_obj.items():
    print(f"日期：{date}")
    print(f"活动：{activities}")
    print("---")

日期：2022-01-01
活动：['A', 'B']
---
日期：2022-01-02
活动：['C']
---
日期：2022-01-03
活动：['D', 'E']
---