title: Distinct like String Manipulation
body: <p>I working on Flutter project. I have query regarding string manipulation. I storing some value like following</p>
  
  <pre><code>String a="31,31,31,31,31,31,31,41,41,41,41,41,41,41,41,41,41,53,53,53,53,53,53,53,53"
  </code></pre>
  
  <p>I have output like Distinct in query</p>
  
  <pre><code>a="31,41,53"
  </code></pre>
  
  <p>may I know how to achieve this function.</p>
  
  <p>Thanks in advance
  Sathish</p>