title: TypeScript - How can pick off some properties from a interface in TypeScript?
body: <p>e.g. I defined a structure for posts like this:</p>
  
  <pre><code>interface PostsInfo{
      md_content    :string;
      id            :number;
      title         :string;
      description   :string;
      update_time   :Date;
      create_time   :Date;
      comment_count :number;
  }
  </code></pre>
  
  <p>then, I need an other interface that without a property which is <code>md_content</code>.</p>
  
  <pre><code>interface PostsInfoWithoutContent{
      // How define?
  }
  </code></pre>
  
  <p>It can fix this right now that make <code>PostsInfo</code> extend <code>PostsInfoWithoutContent</code>, but, if I do like that, how can I do when I need <code>PostsInfoWithoutComment</code> (remove <code>comment_count</code> from <code>PostsInfo</code>)?</p>