How can I set spacing between bars with plot and plot layout?

What I’m trying to do:
Bars for single value list ie., x = [3,5,9] are spaced very far apart. I understand how to control the width, but I cannot make bargap or xgap work. See attached image. Is there documentation that show allowed properties for layout?

What I’ve tried and what’s not working:

Code Sample:

# this is a formatted code snippet.
# paste your code between ``` 
Plot.templates.default = "material_dark"
      self.plotit.data = [
        go.Bar(
          x = feed_count_plot_x,
          y = feed_count_plot_y,
          width = 0.2,
          name = 'sites count bar chart'
        )
      ]
      self.plotit.layout = {
        'title': 'Sites Available and Feed Counts by Site',
        'xaxis': {
          'title': 'sites'
        },
        'yaxis': {'title':'Number of feeds'},
        'xgap':0.3, 
      }

Thank you for the help.
bar-chart-example

Clone link:
share a copy of your app