title: type 'Future<String>' is not a subtype of type 'String' in type cast in flutter
body: <p>I used following function to get user Id from web service </p>
  
  <pre class="lang-dart prettyprint-override"><code>Future&lt;String&gt; getUserid() async {
    final storage = new FlutterSecureStorage();
    // Read value
    String userID = await storage.read(key: 'userid');
    return userID;
  }
  </code></pre>
  
  <p>when useing this function error occured </p>
  
  <blockquote>
    <p>type 'Future' is not a subtype of type 'String' in type cast</p>
  </blockquote>
  
  <p>this is what i have tried</p>
  
  <pre><code>otherFunction() async {
  
    final String userID = await getUserid();
   return userID;
  }
  
  Future&lt;String&gt; getUserid() async {
    final storage = new FlutterSecureStorage();
    // Read value
    String userID = await storage.read(key: 'userid');
    return userID;
  }
  
  print(otherFunction());
  </code></pre>
  
  <p>still error msg shows as  </p>
  
  <blockquote>
    <p>I/flutter (18036): Instance of 'Future'</p>
  </blockquote>