app.py

from datetime import datetime
from flask import Flask, request

app = Flask(__name__)

_people = {
  1: {
    "id": 1,
    "name": "user1",
    "last_signed_at": datetime(2016, 1, 1, 0, 0, 0)
  },
  2: {
    "id": 2,
    "name": "user2",
    "last_signed_at": datetime(2016, 1, 2, 0, 0, 0)
  },
  3: {
    "id": 3,
    "name": "user3",
    "last_signed_at": datetime(2016, 1, 3, 0, 0, 0)
  },
  4: {
    "id": 4,
    "name": "user4",
    "last_signed_at": datetime(2016, 1, 4, 0, 0, 0)
  },
  5: {
    "id": 5,
    "name": "user5",
    "last_signed_at": datetime(2016, 1, 5, 0, 0, 0)
  }
}

@app.route("/people")
def people():
    start = int(request.args.get('start', 0))
    return sorted(_people.values(), key=lambda person: person['last_signed_at'], reverse=True)[start:start+2]

@app.route("/update")
def update():
    i = random.randint(1, 5)
    _people[i]['last_signed_at'] = datetime.now()

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