old_contents: #--coding:utf-8--
  #Platform
  
  class BasePlatform(object):
      """
      A template for codes which are dependent on platform, whatever shell type or system type.
      Redefine members to modify the function.
      """
      def __init__(self, shell = False):
          if shell:
              if os.name == 'posix':
                  return self.Posix()
              if os.name == 'nt':
                  return self.NT()
              return None
          else:
              import platform
              if platform.system()[:6] == 'Darwin':
                  return self.OSX()
              if platform.system()[:5] == 'Linux':
                  return self.Linux()
              if platform.system()[:7] == 'Windows':
                  return self.Windows()
              if platform.system()[:6] == 'CYGWIN':
                  return self.Cygwin()
              return None
          return None
  
      class Common(object):
          """
          Redefine members here for those which will be inherited to all shells and systems.
          """
          pass
  
      class Shell(self.Common):
          """
          Redefine members here for those which will be inherited to all shells.
          """
          pass
  
      class System(self.Common):
          """
          Redefine members here for those which will be inherited to all systems.
          """
          pass
  
      class Posix(self.Shell):
          pass
  
      class NT(self.Shell):
          pass
  
      class OSX(self.System):
          pass
  
      class Linux(self.System):
          pass
  
      class Windows(self.System):
          pass
  
      class Cygwin(self.System):
          pass
  
  if __name__ == '__main__':
      raise EnvironmentError ("DO NOT DIRECTLY RUN THIS TEMPLATE!")
  
new_contents: #--coding:utf-8--
  #Platform
  
  class BasePlatform(object):
      """
      A template for codes which are dependent on platform, whatever shell type or system type.
      Redefine members to modify the function.
      """
      def __init__(self, shell = False):
          if shell:
              if os.name == 'posix':
                  return self.Posix()
              if os.name == 'nt':
                  return self.NT()
              return None
          else:
              import platform
              if platform.system()[:6] == 'Darwin':
                  return self.OSX()
              if platform.system()[:5] == 'Linux':
                  return self.Linux()
              if platform.system()[:7] == 'Windows':
                  return self.Windows()
              if platform.system()[:6] == 'CYGWIN':
                  return self.Cygwin()
              return None
          return None
  
      class Common(object):
          """
          Redefine members here for those which will be inherited to all shells and systems.
          """
          pass
  
      class Shell(Common):
          """
          Redefine members here for those which will be inherited to all shells.
          """
          pass
  
      class System(Common):
          """
          Redefine members here for those which will be inherited to all systems.
          """
          pass
  
      class Posix(Shell):
          pass
  
      class NT(Shell):
          pass
  
      class OSX(System):
          pass
  
      class Linux(System):
          pass
  
      class Windows(System):
          pass
  
      class Cygwin(System):
          pass
  
  if __name__ == '__main__':
      raise EnvironmentError ("DO NOT DIRECTLY RUN THIS TEMPLATE!")
  
subject: Fix the compile error of define classes which derivate from other classes in class.