title: Use the public GitHub API to get all merged pull requests in a JSON format
body: <p>I am trying to get all the <strong>closed and merged</strong> commits on a certain repository using the github API (<a href="https://api.github.com/" rel="nofollow noreferrer">https://api.github.com/</a>), and the only way I have found to do this is to check for commits that are closed (<code>api.github.com/repos/user/repo/pulls?state=closed</code>), then make sure the <code>merged_at</code> is not equal to <code>null</code>, but this is a slow way to do it. Is there a way to make github check if the PR is closed and has been merged at the same time directly in the url? Something like <code>api.github.com/repos/user/repo/pulls?state=closed?is_merged=true</code>? And return all the PRs matching the criteria?</p>
  
  <p>NOTE: this has nothing to do with the <code>/repos/user/repo/pulls/pr_id/merge</code>, because that only tells you if a <strong>single</strong> pull request is merged, and does not search everywhere in the list of PRs.</p>