new_contents: """
  Bar Chart with rounded edges
  ----------------------------
  This example shows how to create a bar chart with rounded edges.
  """
  # category: bar charts
  import altair as alt
  from vega_datasets import data
  
  source = data.seattle_weather()
  
  alt.Chart(source).mark_bar(
      cornerRadiusTopLeft=3,
      cornerRadiusTopRight=3
  ).encode(
      x='month(date):O',
      y='count():Q',
      color='weather:N'
  )
  
subject: add rounded bar example