text: """
  Becker's Barley Trellis Plot
  ----------------------------
  This example shows how to make a Trellis Plot with the barley dataset.
  """
  
  import altair as alt
  from vega_datasets import data
  
  source = data.barley()
  
  chart = alt.Chart(source).mark_point().encode(
      alt.X('median(yield)', scale=alt.Scale(zero = False)),
      alt.Y(
          'variety',
          sort=alt.SortField(field='yield', op='median', order='descending'),
          scale=alt.Scale(rangeStep=20)
      ),
      color='year:N',
      row='site'
  )
  