code: def list_projects(root, backend=os.listdir):
      
      projects = list()
      for project in sorted(backend(root)):
          abspath = os.path.join(root, project)
          if not isproject(abspath):
              continue
          projects.append(project)
      return projects
docs: List projects at `root`
  
      Arguments:
          root (str): Absolute path to the `be` root directory,
              typically the current working directory.