old_contents: """
  Filled Step Chart
  -----------------
  This example shows Google's stock price over time as a step chart with its area filled in. 
  """
  # category: line charts
  import altair as alt
  from vega_datasets import data
  
  chart = alt.Chart(stocks).encode(
      x='date',
      y='price'
  ).transform_filter(
      alt.datum.symbol == 'GOOG'
  )
  
  line = chart.mark_line(color="darkblue")
  area = chart.mark_area(color="lightblue")
  
  (line + area).configure_mark(interpolate='step-after')
  
new_contents: """
  Filled Step Chart
  -----------------
  This example shows Google's stock price over time as a step chart with its area filled in. 
  """
  # category: line charts
  import altair as alt
  from vega_datasets import data
  
  stocks = data.stocks()
  
  chart = alt.Chart(stocks).encode(
      x='date',
      y='price'
  ).transform_filter(
      alt.datum.symbol == 'GOOG'
  )
  
  line = chart.mark_line(color="darkblue")
  area = chart.mark_area(color="lightblue")
  
  (line + area).configure_mark(interpolate='step-after')
  
subject: Update filled_step_chart.py