I am using GAE datastore with python and I want to count and display the number of records between two recent dates. for examples, how many records exist with a time signature between two minutes ago and three minutes ago in the datastore. Thank you.

#!/usr/bin/env python

import wsgiref.handlers
from google.appengine.ext import db
from google.appengine.ext import webapp
from google.appengine.ext.webapp import template
from datetime import datetime

class Voice(db.Model):
    when = db.DateTimeProperty(auto_now_add=True)


class MyHandler(webapp.RequestHandler):
    def get(self):
        voices = db.GqlQuery(
            'SELECT * FROM Voice '
            'ORDER BY when DESC')
        values = {
            'voices': voices
        }
        self.response.out.write(template.render('main.html', values))
    def post(self):
        voice = Voice()
        voice.put()
        self.redirect('/')
        self.response.out.write('posted!')  

def main():
    app = webapp.WSGIApplication([
        (r'.*', MyHandler)], debug=True)
    wsgiref.handlers.CGIHandler().run(app)

if __name__ == "__main__":
    main()