 'burwell_small',
          'source-layer': 'units',
          minzoom: 4,
          maxzoom: 6,
          paint: {
            'line-color': '#555555',
            'line-width': {
              'stops': [
                [4, 0.05],
                [6, 0.3],
              ]
            }
          }
        },
        {
          id: 'small_lines',
          type: 'line',
          source: 'burwell_small',
          'source-layer': 'lines',
          minzoom: 4,
          maxzoom: 6,
          paint: {
    