正确访问嵌套Python字典的问题

nested_dict = {
    "level1_key1": {
        "level2_key1": "value1",
        "level2_key2": {
            "level3_key1": "value2"
        }
    },
    "level1_key2": "value3"
}

value = nested_dict["level1_key1"]["level2_key2"]["level3_key1"]
print(value)  # 输出: value2

# 使用get方法
value = nested_dict.get("level1_key1", {}).get("level2_key2", {}).get("level3_key1")
print(value)  # 输出: value2 或 None

# 使用try-except块
try:
    value = nested_dict["level1_key1"]["level2_key2"]["level3_key1"]
except KeyError:
    value = None
print(value)  # 输出: value2 或 None

if isinstance(nested_dict["level1_key1"], dict) and "level2_key2" in nested_dict["level1_key1"]:
    value = nested_dict["level1_key1"]["level2_key2"]["level3_key1"]
else:
    value = None
print(value)  # 输出: value2 或 None

nested_dict = {
    "level1_key1": {
        "level2_key1": "value1",
        "level2_key2": {
            "level3_key1": "value2"
        }
    },
    "level1_key2": "value3"
}

# 正确访问嵌套字典
value = nested_dict.get("level1_key1", {}).get("level2_key2", {}).get("level3_key1")
print(value)  # 输出: value2

# 处理KeyError
try:
    value = nested_dict["level1_key1"]["level2_key2"]["level3_key1"]
except KeyError:
    value = None
print(value)  # 输出: value2 或 None

# 处理TypeError
if isinstance(nested_dict["level1_key1"], dict) and "level2_key2" in nested_dict["level1_key1"]:
    value = nested_dict["level1_key1"]["level2_key2"]["level3_key1"]
else:
    value = None
print(value)  # 输出: value2 或 None