Отображение данных в ближайшие 15-30 минут в настоящее время - Python

from datetime import timedelta,datetime
 
def faculty(request, faculty_id, show_authors=True, show_titles=True):
    obj = get_object_or_404(models.Faculty, pk=faculty_id)
 
    rooms = models.Classroom.objects.filter(faculty=obj).exclude(room='-').select_related("subject")
    lectures = models.Lecture.objects.filter(room__faculty=obj,semester=settings.SHOW_SEMESTER).select_related("room")
 
    weekdays = []
    for day in models.WORK_DAYS:
        lw = lectures.filter(week_day=day[0])
        timespans = []
        for time in find_timespans(map(lambda x: (x.start, x.end, ), lw)):
            lectures_by_room = []
            for room in rooms:
                lst = lw.filter(start=time[0], end=time[1], room=room)
                lectures_by_room.append(lst)
 
            timespans.append({ "timespan": time, "lectures_grouped": lectures_by_room })
            continue
 
        weekdays.append({ "week_day_visible": day[1], "timespans": timespans })

    d = {
        'faculty': obj,
        'headers': map(lambda x: x.room, rooms),
        'weekdays': weekdays,
        'show_titles': True,
        'show_headers_every_day': False,
        'show_authors': True,
    }
 
    return render_to_response('timetable/faculty.html', RequestContext(request, d))

class Lecture(models.Model):
    subject = models.ForeignKey("Subject",  verbose_name=_("subject"))
    type = models.CharField(max_length=3, choices=SUBJECT_TYPE_CHOICES, blank=True, verbose_name=_("type"))
    author = models.ManyToManyField("Professor", verbose_name=_("author"))
    groups = models.ManyToManyField("Group", verbose_name=_("groups"))
    link = models.CharField(max_length=256, blank=True,  verbose_name=_("external link"))
    room = models.ForeignKey("Classroom",  verbose_name=_("classroom"))
    pogrupis = models.CharField(max_length=4, verbose_name=_("Pogrupis"), choices=POGRUPIAI, blank=True, null=True)
    week_day = models.IntegerField(choices=WORK_DAYS, verbose_name=_("day of week"),)
    week_type = models.IntegerField(choices=WEEK_TYPE_CHOICES, default=0, verbose_name=_("type of week"),)
    start = models.TimeField(verbose_name=_("start time"))
    end = models.TimeField(verbose_name=_("end time"))
    comments = models.TextField(blank=True, verbose_name=_("comments"))
    semester = models.CharField(max_length=10, verbose_name=_("semester"), choices=SEMESTER_CHOICES, default=settings.EDIT_SEMESTER)