title: How to edit chart axes in python pptx - 'GraphicFrame' object has no attribute 'category_axis'
body: <p>I have successfully built a chart with example data and am now trying to format the chart in python. I am attempting to manipulate the axes but have encountered this error:</p>
  
  <p>AttributeError: 'GraphicFrame' object has no attribute 'category_axis'</p>
  
  <p>I believe the problem lies in what the name of the chart is, but I have tried every possible 'name' for the chart that has been created.</p>
  
  <pre><code>chart_data = CategoryChartData()
  chart_data.categories = ['18-24','25-34','35-44','45-54','55-64','65+']
  chart_data.add_series('Series 1', (5,19,23,30,17,7))
  
  x2 = Inches(0)
  y2 = Inches(2)
  cx2 = Inches(3.7)
  cy2 = Inches(.75)
  
  agechart = storyboard1.shapes.add_chart(XL_CHART_TYPE.COLUMN_CLUSTERED, x2, y2, cx2, cy2, chart_data)
  
  category_axis = agechart.category_axis
  category_axis.has_major_gridlines = False
  category_axis.tick_lables.font.size = Pt(8)
  
  value_axis = agechart.value_axis
  value_axis.has_minor_gridlines = False
  value_axis.Maximum_scale = 100.0
  </code></pre>
  
  <p>I expected major gridlines to disappear and the font size to drop to 8 for the category axis, while the value axis' gridlines should've also been dropped and the scale should've been changed. Of course, none of this happens because:</p>
  
  <p>AttributeError: 'GraphicFrame' object has no attribute 'category_axis'</p>
  
  <p>Please help, thanks!</p>