old_contents: # -*- coding: utf-8 -*-
  
  from docutils.nodes import Element, General
  from docutils.parsers.rst import directives
  from sphinx.util.compat import Directive
  
  linked = False # The default value for 'Linked Cells' option
  
  class sagecell(General, Element):
      pass
  
  class SageCell(Directive):
  
      has_content = True
      required_arguments = 0
      optional_arguments = 1
      final_argument_whitespace = False
      option_spec = {
          "linked": directives.unchanged
      }
  
      def run(self):
  
          node = sagecell()
          node['content'] = "\n".join(self.content)
          node['linked'] = self.options.get("linked")
          return [node]
  
  def visit_sagecell_node(self, node):
  
      global linked
  
      if node['linked'] == "true":
          self.body.append("<div class='sage_linked'>")
      elif node['linked'] == "false":
          self.body.append("<div class='sage_unlinked'>")
      elif linked == True:
          self.body.append("<div class='sage_linked'>")
      elif linked == False:
          self.body.append("<div class='sage_unlinked'>")
      else:
          self.body.append("<div class='sage_unlinked'>")
      self.body.append("<script type='text/x-sage'>")
      self.body.append(node['content'])
      self.body.append("</script>")
      self.body.append("</div>")
  
  
  def depart_sagecell_node(self, node):
      pass
  
  def setup(app):
  
      # Register a Docutils node class
      app.add_node(sagecell,
                   html=(visit_sagecell_node, depart_sagecell_node))
      # Register a Docutils directive
      app.add_directive("sagecell", SageCell)
  
new_contents: # -*- coding: utf-8 -*-
  
  from docutils.nodes import Element, General
  from docutils.parsers.rst import directives
  from sphinx.util.compat import Directive
  
  linked = False # The default value for 'Linked Cells' option
  
  class sagecell(General, Element):
      pass
  
  class SageCell(Directive):
  
      has_content = True
      required_arguments = 0
      optional_arguments = 1
      final_argument_whitespace = False
      option_spec = {
          "linked": directives.unchanged
      }
  
      def run(self):
  
          node = sagecell()
          node['content'] = "\n".join(self.content)
          node['linked'] = self.options.get("linked")
          return [node]
  
  def visit_sagecell_node(self, node):
  
      global linked
  
      if node['linked'] == "true":
          self.body.append("<div class='sage_linked'>")
      elif node['linked'] == "false":
          self.body.append("<div class='sage_unlinked'>")
      elif linked == True:
          self.body.append("<div class='sage_linked'>")
      elif linked == False:
          self.body.append("<div class='sage_unlinked'>")
      else:
          self.body.append("<div class='sage_unlinked'>")
      self.body.append("<script type='text/x-sage'>")
      self.body.append(node['content'])
      self.body.append("</script>")
      self.body.append("</div>")
  
  def depart_sagecell_node(self, node):
      pass
  
  def setup(app):
  
      # Register a Docutils node class
      app.add_node(sagecell,
                   html=(visit_sagecell_node, depart_sagecell_node))
      # Register a Docutils directive
      app.add_directive("sagecell", SageCell)
  
subject: Fix typo