title: Future String in flutter
body: <p>So I have a function that returns a value that is of future. When this function executes I want to extract the string from the future. How should I do this?</p>
  
  <pre><code>Future&lt;String&gt; coverImage(id, space) {
    String link = 'https://cdn.contentful.com/spaces/$space/assets/$id?access_token=1d4932ce2b24458e85ded26532bb81184e0d79c1a16c5713ec3ad391c2e8f5b3';
    return http.get(link).then((response) =&gt; decodeToImage(decodeJson(response.body)));   
  }
  </code></pre>
  
  <p>this function return <code>Future&lt;String&gt;</code>, i want to extract to string when i am using with image widget</p>