'set-cookie' => 'cookie=value; path=/;

'_request' => bless( {
         '_method' => 'GET',
         '_uri' => bless( do{\(my $o = 'http://some_api:1234/')}, 'URI::http' ),

curl http://some_api:1234/ -vvv -c /tmp/cookie.txt
*   Trying 10.0.6.12...
* TCP_NODELAY set
* Connected to some_api (10.0.6.12) port 1234 (#0)
> GET / HTTP/1.1
> Host: some_api:1234
> User-Agent: curl/7.52.1
> Accept: */*
> 
< HTTP/1.1 200 OK
< Content-Language: en
< Content-Type: application/json; charset=utf-8
* Added cookie cookie="value" for domain some_api, path /, expire 1632312905

cat /tmp/cookie.txt 
# Netscape HTTP Cookie File
# https://curl.haxx.se/docs/http-cookies.html
# This file was generated by libcurl! Edit at your own risk.

#HttpOnly_admin_api     FALSE   /       TRUE    1632312905