code: def get_custom_functions():
      
      def get_setting(*args):
          try:
              return getattr(settings, args[0])
          except AttributeError as e:
              raise TemplateSyntaxError(str(e))
  
      if hasattr(get_custom_functions, '_custom_functions'):
          return get_custom_functions._custom_functions
      get_custom_functions._custom_functions = {sass.SassFunction('get-setting', ('key',), get_setting)}
      for name, func in getattr(settings, 'SASS_PROCESSOR_CUSTOM_FUNCTIONS', {}).items():
          try:
              if isinstance(func, six.string_types):
                  func = import_string(func)
          except Exception as e:
              raise TemplateSyntaxError(str(e))
          else:
              if not inspect.isfunction(func):
                  raise TemplateSyntaxError("{} is not a Python function".format(func))
              if six.PY2:
                  func_args = inspect.getargspec(func).args
              else:
                  func_args = inspect.getfullargspec(func).args
              sass_func = sass.SassFunction(name, func_args, func)
              get_custom_functions._custom_functions.add(sass_func)
      return get_custom_functions._custom_functions
docs: Return a dict of function names, to be used from inside SASS