new_contents: from collections import namedtuple
  
  # A tuple used in language registration/discovery
  LanguageDesc = namedtuple('LanguageDesc',
                            'name extension description metamodel')
  
  # A tuple used in generators registration/discovery
  # `generator` attribute is a callable of the form:
  # def generator(model, output_folder)
  GeneratorDesc = namedtuple('GeneratorDesc',
                             'language target description generator')
  
subject: Add named tuples for language/generator registration