Does it support graphql - variables?

Graphql `query` works well.
How can we set `variable` in `query` or `mutation` components?

There is a [HTTP Plugin ](https://marketplace.visualstudio.com/items?itemName=humao.rest-client)for VS-Code which handles `graphql` along with `query-variables`.
Is is possible or can be done with `coc-post` ?

```
POST https://api.github.com/graphql
Content-Type: application/json
Authorization: Bearer xxx
X-REQUEST-TYPE: GraphQL

query ($name: String!, $owner: String!) {
repository(name: $name, owner: $owner) {
name
fullName: nameWithOwner
description
diskUsage
forkCount
stargazers(first: 5) {
totalCount
nodes {
login
name
}
}
watchers {
totalCount
}
}
}

# QUERY - VARIABLES
{
"name": "vscode-restclient",
"owner": "Huachao"
}
```