old_contents: from django import template
  
  register = template.Library()
  
  
  @register.filter(name='is_list')
  def is_list(value):
      return isinstance(value, list)
  
  
  @register.filter(name='is_dict')
  def is_dict(value):
      return isinstance(value, dict)
  
new_contents: from django import template
  
  register = template.Library()
  
  
  @register.filter(name='is_list')
  def is_list(value):
      return isinstance(value, list)
  
  
  @register.filter(name='is_dict')
  def is_dict(value):
      return isinstance(value, dict)
  
  
  @register.filter(name='before_comma')
  def split(value):
      return value.split(',')[0]
  
subject: add specific tag