title: ImportError: Plotly express requires pandas to be installed
body: <p>When I try to import plotly.express I get the error:</p>
  <pre><code>ImportError: Plotly express requires pandas to be installed.
  </code></pre>
  <p>The installation notes did not mention having to install anything additional. I can import plotly on its own, I only get the error when importing plotly.express. Any ideas on how to fix this?</p>