title: Error when going from dataframe to excel file in Julia
body: <p>I am trying to export a dataframe to xlsx</p>
  <pre><code>df |&gt; XLSX.writexlsx(&quot;df.xlsx&quot;)
  </code></pre>
  <p>and am getting this error:</p>
  <pre><code>ERROR: Unsupported datatype String31 for writing data to Excel file. Supported data types are Union{Missing, Bool, Float64, Int64, Dates.Date, Dates.DateTime, Dates.Time, String} or XLSX.CellValue.
  </code></pre>
  <p>I cannot find anyting about <code>String31</code> utilizing Google. Is there a &quot;transform&quot; that I need to perform on the df beforehand?</p>