How to filter in grpahql github api by MergeableState

So I have the following block of code that returns me list of PR with their mergeability status such as ‘MERGEABLE’, ‘CONFLICTING’, etc. I want to understand if there is anyway to filter inline by mergeablestate. I can filter the result obtained after this using js or anything else. I wanted to understand for any way to do it directly in graphql script. Looked up the docs could not find a way

{
      repository(owner: "fireship-io", name: "git-sticker") {
        pullRequests(first: 1, states: [OPEN]) {
          nodes {
            id
            number
            changedFiles
            deletions
            mergeable
            author {
              url
            }
          }
        }
      }
    }

I tried

pullRequests(first: 1, states: [OPEN], mergeable: [MERGEABLE))

But got an error saying mergeable is not a valid argument for pullRequests.