i am getting a error when i am running the flask application with python to plot graphs on web ui

from flask import Flask, render_template

app = Flask(__name__)


@app.route("/home")
def home():
    plot_data = [
        ("3-01-2020", 6),
        ("3-02-2020", 13),
        ("3-03-2020", 14),
        ("3-04-2020", 41),
        ("1-05-2020", 10),
        ("3-06-2020", 0),
        ("3-07-2020", 16),
        ("3-08-2020", 10),
        ("3-09-2020", 17),
        ("3-10-2020", 19),
    ]
    labels = []
    values = []
    for row in plot_data:
        labels.append(row[0])
        values.append(row[1])

    print(labels)
    print(values)
    return render_template('graph.html', labels=labels, values=values)


if __name__ == "__main__":
    app.run(debug=True)