Please tell me how to use proxy authentication?

I want to use localhost proxy to access my remote service, but failed, remote service return 407 Proxy Authorization Required I use follow cmd: oha -n 100 --burst-delay 2s --burst-rate 10 -a "admin:123432" -x http://127.0.0.1:38520 "https://api.test.example.com

oha --debug Request { method: GET, uri: /geoip, version: HTTP/1.1, headers: { "accept": "*/*", "accept-encoding": "gzip, compress, deflate, br", "user-agent": "oha/1.8.0", "host": "api.ip.sb", "authorization": "Basic YWRtaW46MTIzNDMy", }, body: Full { data: None, }, } Error: no upgrade available