human
I wrote the below code

    if cl.date_hierarchy:
        field_name = cl.date_hierarchy
        year_field = ('%s__year' % field_name)
        month_field = ('%s__month' % field_name)
        day_field = ('%s__day' % field_name)
        field_generic = ('%s__' % field_name)
        year_lookup = cl.params.get(year_field)
        month_lookup = cl.params.get(month_field)
        day_lookup = cl.params.get(day_field)
        def link(filters):
            return cl.get_query_string(filters, [field_generic])
        if (not (year_lookup or month_lookup or day_lookup)):
            date_range = cl.queryset.aggregate(first=models.Min(field_name), last=models.Max(field_name))
            if (date_range['first'] and date_range['last']):
                if (date_range['first'].year == date_range['last'].year):
                    year_lookup = date_range['first'].year
                    if (date_range['first'].month == date_range['last'].month):
                        month_lookup = date_range['first'].month
        if (year_lookup and month_lookup and day_lookup):
            day = datetime.date(int(year_lookup), int(month_lookup), int(day_lookup))
            return {'show': True, 'back': {'link': link({year_field: year_lookup, month_field: month_lookup}), 'title': capfirst(formats.date_format(day, 'YEAR_MONTH_FORMAT'))}, 'choices': [{'title': capfirst(formats.date_format(day, 'MONTH_DAY_FORMAT'))}]}
        elif (year_lookup and month_lookup):
            days = cl.queryset.filter(**{year_field: year_lookup, month_field: month_lookup})
            days = getattr(days, 'dates')(field_name, 'day')
            return {'show': True, 'back': {'link': link({year_field: year_lookup}), 'title': str(year_lookup)}, 'choices': [{'link': link({year_field: year_lookup, month_field: month_lookup, day_field: day.day}), 'title': capfirst(formats.date_format(day, 'MONTH_DAY_FORMAT'))} for day in days]}
        elif year_lookup:
            months = cl.queryset.filter(**{year_field: year_lookup})
            months = getattr(months,...

What's a good function header?
 ... Here's a good function header?
assistant
#Here's a good function header.

@register.inclusion_tag('admin/date_hierarchy.html')
def date_hierarchy(cl):