title: Python: openpyxl how to read a cell font color
body: <p>I have tried to print <code>some_cell.font.color.rgb</code> and got various results.</p>
  
  <p>For some I got what I want (like "<code>FF000000</code>"), but for others it gives me <code>Value must be type 'basetring'</code>. I assume that the latter is because I haven't actually defined the font color for these cells.</p>
  
  <p>I'm using openpyxl 2.2.2</p>