如何解决以下python键错误

my_dict = {'key1': 'value1', 'key2': 'value2'}
if 'key3' in my_dict:
    # 键存在，执行相应的操作
    value = my_dict['key3']
else:
    # 键不存在，执行相应的操作
    print("键不存在")

my_dict = {'key1': 'value1', 'key2': 'value2'}
value = my_dict.get('key3', '默认值')

my_dict = {'key1': 'value1', 'key2': 'value2'}
try:
    value = my_dict['key3']
except KeyError:
    # 键错误发生时执行相应的操作
    print("键错误发生")