code: def module(self):
          
  
          if self._module is None:
              if self.library is None:
                  raise ValueError(
                      "Backend '%s' doesn't specify a library attribute" % self.__class__)
  
              try:
                  if '.' in self.library:
                      mod_path, cls_name = self.library.rsplit('.', 1)
                      mod = import_module(mod_path)
                      self._module = getattr(mod, cls_name)
                  else:
                      self._module = import_module(self.library)
              except (AttributeError, ImportError):
                  raise ValueError("Couldn't load %s backend library" % cls_name)
  
          return self._module
docs: The module specified by the ``library`` attribute.