old_contents: """Python script Exporter class"""
  
  #-----------------------------------------------------------------------------
  # Copyright (c) 2013, the IPython Development Team.
  #
  # Distributed under the terms of the Modified BSD License.
  #
  # The full license is in the file COPYING.txt, distributed with this software.
  #-----------------------------------------------------------------------------
  
  #-----------------------------------------------------------------------------
  # Imports
  #-----------------------------------------------------------------------------
  
  from IPython.utils.traitlets import Unicode
  
  from .templateexporter import TemplateExporter
  
  #-----------------------------------------------------------------------------
  # Classes
  #-----------------------------------------------------------------------------
  
  class PythonExporter(TemplateExporter):
      """
      Exports a Python code file.
      """
      
      file_extension = Unicode(
          'py', config=True, 
          help="Extension of the file that should be written to disk")
  
      def _raw_mimetype_default(self):
          return 'application/x-python'
  
  
new_contents: """Python script Exporter class"""
  
  #-----------------------------------------------------------------------------
  # Copyright (c) 2013, the IPython Development Team.
  #
  # Distributed under the terms of the Modified BSD License.
  #
  # The full license is in the file COPYING.txt, distributed with this software.
  #-----------------------------------------------------------------------------
  
  #-----------------------------------------------------------------------------
  # Imports
  #-----------------------------------------------------------------------------
  
  from IPython.utils.traitlets import Unicode
  
  from .templateexporter import TemplateExporter
  
  #-----------------------------------------------------------------------------
  # Classes
  #-----------------------------------------------------------------------------
  
  class PythonExporter(TemplateExporter):
      """
      Exports a Python code file.
      """
      
      file_extension = Unicode(
          'py', config=True, 
          help="Extension of the file that should be written to disk")
  
      def _raw_mimetype_default(self):
          return 'application/x-python'
  
      mime_type = Unicode('text/x-python', config=True,
          help="MIME type of the result file, for HTTP response headers."
          )
  
subject: Add MIME types to nbconvert exporters