curl --location --request PATCH 'https://api.victorops.com//api-public/v1/policies//oncall/user' \
--header 'X-VO-Api-Id;' \
--header 'X-VO-Api-Key;' \
--header 'Content-Type: application/json' \
--data-raw '{
"fromUser": "string",
"toUser": "string"
}'
{
"result": "string"
}