old_contents: from datetime import date
  from datetime import timedelta
  
  from django.utils import timezone
  
  from books.models import Transaction
  
  
  def get_months_transactions():
      today = timezone.now()
      first_day_of_a_month = date(today.year, today.month, 1)
      qs = Transaction.objects.filter(created__gte=first_day_of_a_month)
      return qs
  
  
  def get_last_months_transactions():
      first_day_of_a_month = timezone.now().replace(day=1)
      last_month = first_day_of_a_month - timedelta(days=1)
      first_day_of_last_month = date(last_month.year, last_month.month, 1)
      qs = Transaction.objects.filter(created__gte=first_day_of_last_month)
      return qs
  
  
  def get_this_years_transactions():
      today = timezone.now()
      first_day_of_this_year = date(today.year, 1, 1)
      qs = Transaction.objects.filter(created__gte=first_day_of_this_year)
      return qs
  
new_contents: from datetime import datetime
  from datetime import timedelta
  
  from django.utils import timezone
  
  from books.models import Transaction
  
  
  def get_months_transactions():
      today = timezone.now()
      first_day_of_a_month = datetime(today.year, today.month, 1,
                                      tzinfo=today.tzinfo)
      qs = Transaction.objects.filter(created__gte=first_day_of_a_month)
      return qs
  
  
  def get_last_months_transactions():
      first_day_of_a_month = timezone.now().replace(day=1)
      last_month = first_day_of_a_month - timedelta(days=1)
      first_day_of_last_month = datetime(last_month.year, last_month.month, 1,
                                         tzinfo=last_month.tzinfo)
      qs = Transaction.objects.filter(created__gte=first_day_of_last_month)
      return qs
  
  
  def get_this_years_transactions():
      today = timezone.now()
      first_day_of_this_year = datetime(today.year, 1, 1, tzinfo=today.tzinfo)
      qs = Transaction.objects.filter(created__gte=first_day_of_this_year)
      return qs
  
subject: Add service functions to get transactions by time