title: LibreOffice Calc: check if cell is a formula
body: <p>I want to implement some conditional formatting in LibreOffice Calc (v5.4.4.2 but can upgrade) that will highlight cells whose values are calculated through a formula rather than entered directly.</p>
  
  <p>For example, a cell containing</p>
  
  <pre><code>=A3
  </code></pre>
  
  <p>will be highlighted, while</p>
  
  <pre><code>Hello world!
  </code></pre>
  
  <p>in cell A3 will not be.</p>
  
  <p>I understand conditional formatting, etc; I just need to determine the correct formulae for checking if a cell actually contains a formula.</p>