Tornado / Flask help needed

[snippsat]

I tried the same thing using the Flask example:

To clean it up a little.
Using import io and png_output = io.BytesIO()
All imports out of function.
For running it,you most use this address browser http://127.0.0.1:5000/simple.png

from flask import Flask, make_response
import datetime, random
import io
from matplotlib.backends.backend_agg import FigureCanvasAgg as FigureCanvas
from matplotlib.figure import Figure
from matplotlib.dates import DateFormatter

app = Flask(__name__)
@app.route("/simple.png")
def simple():
    fig = Figure()
    ax = fig.add_subplot(111)
    x = [ ]
    y = [ ]
    now = datetime.datetime.now()
    delta = datetime.timedelta(days=1)
    for i in range(10):
        x.append(now)
        now += delta
        y.append(random.randint(0, 1000))
    ax.plot_date(x, y, '-')
    ax.xaxis.set_major_formatter(DateFormatter('%Y-%m-%d'))
    fig.autofmt_xdate()
    canvas = FigureCanvas(fig)
    png_output = io.BytesIO()
    canvas.print_png(png_output)
    response = make_response(png_output.getvalue())
    response.headers['Content-Type'] = 'image/png'
    return response

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