input: Write a python function to list reminders, add a new reminder, and then remove a reminder by index.
  assert len(reminders) == 2
  add_reminder({"date": "2021-12-25", "title": "Christmas", "description": "Celebrate Christmas!"})
  assert len(reminders) == 3
  remove_reminder(0)
  assert len(reminders) == 2
output: reminders = [
      {"date": "2021-10-31", "title": "Halloween", "description": "Celebrate Halloween!"},
      {"date": "2021-11-25", "title": "Thanksgiving", "description": "Celebrate Thanksgiving!"},
  ]
  
  def list_reminders():
      return reminders
  
  def add_reminder(reminder):
      reminders.append(reminder)
  
  def remove_reminder(index):
      if 0 <= index < len(reminders):
          del reminders[index]