old_contents: 
  import re
  
  from django.utils.translation import ugettext_lazy as _
  from django.utils.safestring import mark_safe
  
  from sorl.thumbnail import get_thumbnail
  
  
  def round_number(value, decimal_places=2, down=False):
  
      assert decimal_places > 0
      factor = 1.0 ** decimal_places
      sign = -1 if value < 0 else 1
      return int(value * factor + sign * (0 if down else 0.5)) / factor
  
  
  def format_number(value):
  
      append_comma = lambda match_object: "%s," % match_object.group(0)
  
      value = "%.2f" % float(value)
      value = re.sub("(\d)(?=(\d{3})+\.)", append_comma, value)
  
      return value
  
  
  def format_price(price, round_price=False):
      price = float(price)
      return format_number(round_number(price) if round_price else price)
  
  
  def get_show_on_site_link(url):
      return mark_safe(
          '<a href="%s" target="_blank">%s</a>' % (url, _('Show on site')))
  
  
  def get_preview(field, width=100):
  
      if not field:
          return '-----'
      try:
          url = get_thumbnail(field.file, str(width)).url
      except IOError:
          return _('Image not found')
  
      return mark_safe('<img src="%s" style="width: %spx;" title="%s" />' % (
          url, width, field.path))
  
new_contents: 
  import re
  
  from django.utils import timezone
  from django.utils.translation import ugettext_lazy as _
  from django.utils.safestring import mark_safe
  
  from sorl.thumbnail import get_thumbnail
  
  
  def round_number(value, decimal_places=2, down=False):
  
      assert decimal_places > 0
      factor = 1.0 ** decimal_places
      sign = -1 if value < 0 else 1
      return int(value * factor + sign * (0 if down else 0.5)) / factor
  
  
  def format_number(value):
  
      append_comma = lambda match_object: "%s," % match_object.group(0)
  
      value = "%.2f" % float(value)
      value = re.sub("(\d)(?=(\d{3})+\.)", append_comma, value)
  
      return value
  
  
  def format_price(price, round_price=False):
      price = float(price)
      return format_number(round_number(price) if round_price else price)
  
  
  def get_show_on_site_link(url):
      return mark_safe(
          '<a href="%s" target="_blank">%s</a>' % (url, _('Show on site')))
  
  
  def get_preview(field, width=100):
  
      if not field:
          return '-----'
      try:
          url = get_thumbnail(field.file, str(width)).url
      except IOError:
          return _('Image not found')
  
      return mark_safe('<img src="%s" style="width: %spx;" title="%s" />' % (
          url, width, field.path))
  
  
  def get_file_upload_path(folder, filename):
      tz_now = timezone.localtime(timezone.now()).strftime('%Y_%m_%d_%H_%M')
      return '%s/%s.%s' % (folder, tz_now, filename.split('.')[-1])
  
subject: Create `get_file_upload_path` method.