title: Is there any quick way to get comment count of all open pull request
body: <p>I have a requirement to find count of comments in all open pull request of a repository</p>
  
  <p>Only way i know is to get all open pull request from a repo and iterate each pull request and perform call like this</p>
  
  <pre><code>GET /repos/:owner/:repo/pulls/:pull_number/comments
  </code></pre>
  
  <p>and sum up those responses, But it is too costly</p>
  
  <p>I also tried with this method ( Find review comments on all PR in a repo)</p>
  
  <pre><code>GET /repos/:owner/:repo/pulls/comments
  </code></pre>
  
  <p>and passed state = open as query param like this</p>
  
  <pre><code>https://api.github.com/repos/angular/angular/pulls/comments?per_page=30&amp;state=open
  </code></pre>
  
  <p>But it returns review comments of all pull requests</p>
  
  <p>Any efforts will be appreciated</p>