title: array find duplicate values where a value repeats at a certain value
body: <p>I have the following array with dates:</p>
  
  <pre><code>Array ( [0] =&gt; 2019-10-01 [1] =&gt; 2019-10-03 [2] =&gt; 2019-10-04 [3] =&gt; 2019-10-04 [4] =&gt; 2019-11-01 [5] =&gt; 2019-11-01 [6] =&gt; 2019-11-01 [7] =&gt; 2019-11-02 [8] =&gt; 2019-11-04 ) 
  </code></pre>
  
  <p>I want to make a new array finding duplicate values but only when a value appears 3 times so the new array will look</p>
  
  <pre><code>Array ( [0] =&gt; 2019-11-01 ) 
  </code></pre>
  
  <p>any help please?</p>