code: def get_issue_classes(self,backend = None,enabled = True,sort = None,**kwargs):
          
          if backend is None:
              backend = self.backend
  
          query = {'project_issue_classes.project' : self}
          if enabled is not None:
              query['project_issue_classes.enabled'] = enabled
  
          issue_classes = backend.filter(self.IssueClass,query,
                                     **kwargs)
  
  
          if sort is not None:
              issue_classes = issue_classes.sort(sort)
  
          return issue_classes
docs: Retrieves the issue classes for a given backend
  
          :param backend: A backend to use. If None, the default backend will be used
          :param enabled: Whether to retrieve enabled or disabled issue classes.
                          Passing `None` will retrieve all issue classes.