"""
Filled Step Chart
-----------------
This example shows Google's stock price over time as a step chart with its area filled in and its line emphasized.
"""
# category: line charts
import altair as alt
from vega_datasets import data

source = data.stocks()

(
    alt.Chart(source)
    .mark_area(color="lightblue", interpolate="step-after", line=True)
    .encode(x="date", y="price")
    .transform_filter(alt.datum.symbol == "GOOG")
)
