如何在创建身份角色之前检查该角色是否存在？

from tencentcloud.common import credential
from tencentcloud.common.profile.client_profile import ClientProfile
from tencentcloud.common.profile.http_profile import HttpProfile
from tencentcloud.iam.v20200116 import iam_client, models

# 配置访问密钥和区域
cred = credential.Credential("your-secret-id", "your-secret-key")
httpProfile = HttpProfile()
httpProfile.endpoint = "iam.tencentcloudapi.com"
clientProfile = ClientProfile()
clientProfile.httpProfile = httpProfile

# 创建 API 客户端对象
client = iam_client.IamClient(cred, "ap-guangzhou", clientProfile)

# 查询角色信息
request = models.DescribeRoleRequest()
request.RoleName = "your-role-name"

# 发起 API 请求
response = client.DescribeRole(request)

# 判断角色是否存在
if response.Role.RoleName:
    print("角色存在")
else:
    print("角色不存在")