在python中创建一个简单的字典需要帮助

# 创建一个简单的字典
my_dict = {'key1': 'value1', 'key2': 'value2', 'key3': 'value3'}

# 访问字典中的值
print(my_dict['key1'])  # 输出: value1

# 修改字典中的值
my_dict['key2'] = 'new value'
print(my_dict['key2'])  # 输出: new value

# 添加新的键值对
my_dict['key4'] = 'value4'
print(my_dict['key4'])  # 输出: value4

# 删除键值对
del my_dict['key3']
print(my_dict.get('key3'))  # 输出: None

# 获取字典的键和值
print(my_dict.keys())    # 输出: dict_keys(['key1', 'key2', 'key4'])
print(my_dict.values())  # 输出: dict_values(['value1', 'new value', 'value4'])

# 判断键是否存在
print('key1' in my_dict)  # 输出: True
print('key3' in my_dict)  # 输出: False