title: What does "can only be default-imported using the 'esModuleInterop' flag" mean?
body: <p>I am getting the following error:</p>
  
  <pre><code>lib/app.ts:1:8 - error TS1259: Module '"mongoose-sequence"' can only be default-imported using the 'esModuleInterop' flag
  </code></pre>
  
  <p>on the following line of code:</p>
  
  <pre><code>import _ from 'mongoose-sequence';
  </code></pre>
  
  <p>Now, I'm happy to admit I'm missing something with the whole "underscore as a function name" thing, but the error makes no sense, as the <code>esModuleInterop</code> flag is absolutely, positively set to <code>true</code> in my ts.config file.</p>
  
  <p>I am trying to import this:</p>
  
  <pre><code>declare module 'mongoose-sequence' {
    import mongoose = require('mongoose');
    var _: (schema: mongoose.Schema, options?: Object) =&gt; void;
    export = _;
  </code></pre>
  
  <p>from the mongoose-sequence DefinitelyTyped definition.</p>
  
  <p>What am I missing?</p>