title: Get the value between the parentheses, multiple matches in one string
body: <p>My spreadsheet has a column with value like this string:</p>
  
  <pre><code>some text (text1) some test (text2) (text1)
  </code></pre>
  
  <p>How do I get all values between parentheses? The result I am looking for is:</p>
  
  <pre><code>text1, text2
  </code></pre>
  
  <p>Even if <code>text1, text2... testn</code> is present in the cell multiple times, I need it in the result only once.</p>
  
  <p>I found a function <code>GetParen</code> here: <a href="https://stackoverflow.com/questions/8058032/get-the-value-between-the-brackets">Get the value between the brackets</a></p>
  
  <p>It is helpful, but it gives the fist available value in the parentheses and ignores the rest.  </p>