Add example of plotting a chart with multiple lines

multi_line_chart_example.py

@@ -0,0 +1,15 @@
+from database.ohlc import ohlc
+from datetime import datetime, timedelta
+
+from line_chart import LineChart
+from plot import plot
+
+end_date = datetime.today().date()
+start_date = (end_date - timedelta(days = 90))
+data = ohlc('SPX.XO', '1d', start_date = start_date, end_date = end_date)
+
+line_chart = LineChart(
+    x = data['Timestamp'], 
+    values = [data['High'], data['Low']]
+)
+plot(line_chart)