MAINT: use population URL in example to allow tests to run offline
@@ -7,7 +7,7 @@ This example shows a basic bar chart with a single bar singled out for a highlig
import altair as alt
from vega_datasets import data
-population = data.population()
+population = data.population.url
alt.Chart(population).mark_bar().encode(
x="year:O",
