new_contents: # -*- coding: utf-8 -*-
  
  from django import template
  from django.template import Node, NodeList, Variable, VariableDoesNotExist
  
  register = template.Library()
  
  def do_startswith(parser, token, negate):
      try:
          # split_contents() knows not to split quoted strings.
          tag_name, string, start_string = token.split_contents()
      except ValueError:
          raise template.TemplateSyntaxError("%r tag requires two arguments" % token.contents.split()[0])
      if not (start_string[0] == start_string[-1] and start_string[0] in ('"', "'")):
          raise template.TemplateSyntaxError ("%r start strings argument should be in quotes" % tag_name)
      
      end_tag = 'end' + tag_name
      nodelist_true = parser.parse(('else', end_tag))
      token = parser.next_token()
      if token.contents == 'else':
          nodelist_false = parser.parse((end_tag,))
          parser.delete_first_token()
      else:
          nodelist_false = NodeList()
      return IfStartsWithNode(string, start_string, nodelist_true, nodelist_false, negate)
  
  class IfStartsWithNode(Node):
      def __init__(self, string, start_string, nodelist_true, nodelist_false, negate):
          self.start_string, self.string = Variable(start_string), Variable(string)
          self.nodelist_true, self.nodelist_false = nodelist_true, nodelist_false
          self.negate = negate
          self.negate = negate
  
      def __repr__(self):
          return "<IfStartsWithNode>"
  
      def render(self, context):
          try:
              string = self.string.resolve(context)
          except VariableDoesNotExist:
              string = None
          try:
              start_string = self.start_string.resolve(context)
          except VariableDoesNotExist:
              start_string = None
                      
          if (self.negate and not string.startswith(start_string)) or (not self.negate and string.startswith(start_string)):
              return self.nodelist_true.render(context)
          return self.nodelist_false.render(context)
  
  #@register.tag
  def ifstartswith(parser, token):
      return do_startswith(parser, token, False)
  ifstartswith = register.tag(ifstartswith)
  
  #@register.tag
  def ifnotstartswith(parser, token):
      return do_startswith(parser, token, True)
  ifnotstartswith = register.tag(ifnotstartswith)
  
subject: Add startswith template tag (#1007)