title: Power BI date difference between rows in a single column with conditions
body: <p>I have a table with the columns: Account, Current stage, Old Stage, New Stage, Change date (see example below).  I need to find the datediff for each stage length on accounts. Dax or Power Query, whichever is easier. Is it even possible to get the results seen in the sample below?</p>
  <pre><code>Account   Current Stage   Old Stage    New Stage    Change Date    Stage Length(days)
  ABC       Testing         Demo         Testing      1/1/2022           31
  ABC       Testing         Testing                   2/1/2022    
  XYZ       Completed       Demo         Testing      1/1/2022           31
  XYZ       Completed       Testing      Completed    2/1/2022           59
  XYZ       Completed       Completed                 4/1/2022    
  </code></pre>