old_contents: """Embed graphics into HTML Exporter class"""
  
  import base64
  import re
  from nbconvert.exporters.html import HTMLExporter
  
  try:
      from urllib.request import urlopen  # py3
  except ImportError:
      from urllib2 import urlopen
  
  class EmbedHTMLExporter(HTMLExporter):
      def replfunc(self, match):
          """Replace source url or file link with base64 encoded blob."""
          url = match.group(1)
          imgformat = url.split('.')[-1]
          if url.startswith('http'):
              data = urlopen(url).read()
          elif url.startswith('data'):
              img = '<img src="' + url + '" ' + match.group(2) + ' />'
              return img
          else:
              with open(url, 'rb') as f:
                  data = f.read()
  
          self.log.info("embedding url: %s, format: %s" % (url, imgformat))
          b64_data = base64.b64encode(data).decode("utf-8")
          if imgformat == "svg":
              img = '<img src="data:image/svg+xml;base64,' + \
                  b64_data + '"  ' + match.group(2) + '/>'
          elif imgformat == "pdf":
              img = '<img src="data:application/pdf;base64,' + \
                  b64_data + '"  ' + match.group(2) + '/>'
          else:
              img = '<img src="data:image/' + imgformat + \
                  ';base64,' + b64_data + '" ' + match.group(2) + ' />'
          return img
  
      def from_notebook_node(self, nb, resources=None, **kw):
          output, resources = super().from_notebook_node(nb, resources)
  
          regex = re.compile('<img\s+src="(\S+)"\s*(\S*)\s*')
  
          embedded_output = regex.sub(self.replfunc, output)
          return embedded_output, resources
  
new_contents: """Embed graphics into HTML Exporter class"""
  
  import base64
  import re
  from nbconvert.exporters.html import HTMLExporter
  
  try:
      from urllib.request import urlopen  # py3
  except ImportError:
      from urllib2 import urlopen
  
  
  class EmbedHTMLExporter(HTMLExporter):
      def replfunc(self, match):
          """Replace source url or file link with base64 encoded blob."""
          url = match.group(1)
          imgformat = url.split('.')[-1]
          if url.startswith('http'):
              data = urlopen(url).read()
          elif url.startswith('data'):
              img = '<img src="' + url + '" ' + match.group(2) + ' />'
              return img
          else:
              with open(url, 'rb') as f:
                  data = f.read()
  
          self.log.info("embedding url: %s, format: %s" % (url, imgformat))
          b64_data = base64.b64encode(data).decode("utf-8")
          if imgformat == "svg":
              img = '<img src="data:image/svg+xml;base64,' + \
                  b64_data + '"  ' + match.group(2) + '/>'
          elif imgformat == "pdf":
              img = '<img src="data:application/pdf;base64,' + \
                  b64_data + '"  ' + match.group(2) + '/>'
          else:
              img = '<img src="data:image/' + imgformat + \
                  ';base64,' + b64_data + '" ' + match.group(2) + ' />'
          return img
  
      def from_notebook_node(self, nb, resources=None, **kw):
          output, resources = super(EmbedHTMLExporter, self).from_notebook_node(nb, resources)
  
          regex = re.compile('<img\s+src="(\S+)"\s*(\S*)\s*')
  
          embedded_output = regex.sub(self.replfunc, output)
          return embedded_output, resources
  
subject: Fix super() call