new_contents: """
  mdownx.admonitionicon
  An extension for Python Markdown.
  Add spans for adding icons.
  
  MIT license.
  
  Copyright (c) 2014 Isaac Muse <isaacmuse@gmail.com>
  
  Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
  
  The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
  
  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  """
  from __future__ import unicode_literals
  from __future__ import absolute_import
  from ..extensions import Extension
  from ..treeprocessors import Treeprocessor
  from ..util import etree
  
  
  class AdmonitionIconTreeprocessor(Treeprocessor):
      CLASSNAME_ICON = 'admonition-icon'
  
      def run(self, root):
          """ Add admontion icon """
          for tag in root.iter("div"):
              classes = tag.attrib.get("class", "").split()
              if "admonition" in classes:
                  span = etree.Element('span')
                  span.set('class', self.CLASSNAME_ICON)
                  tag.insert(0, span)
          return root
  
  
  class AdmonitionIconExtension(Extension):
      def extendMarkdown(self, md, md_globals):
          """Add AdmonitionIconTreeprocessor to Markdown instance"""
  
          adicon = AdmonitionIconTreeprocessor(md)
          md.treeprocessors.add("admonitionicon", adicon, ">inline")
          md.registerExtension(self)
  
  
  def makeExtension(configs={}):
      return AdmonitionIconExtension(configs=configs)
  
subject: Add admontionicon extension