title: How to reverse a Map in dart? Is there any build in function
body: <p>There is a map. I want to reverse it. is there any inbuilt function for that in dart?</p>
  
  <pre><code>{203: 5, 201: 3, 204: 1}
  </code></pre>
  
  <p>This the current Map i have.</p>
  
  <pre><code>{204: 1,201: 3:203: 5}
  </code></pre>
  
  <p>This is the results i want to get.</p>
  
  <p>Thank You!</p>