code: def get_valid_paths(self, path):
          
          (parent, subdirs, files) = path
          if set(self.runs).intersection(subdirs):
              return [parent]
          if not any([parent.endswith(os.sep + r) for r in self.runs]) and \
                  len(glob.glob(os.path.join(parent, "vasprun.xml*"))) > 0:
              return [parent]
          return []
docs: There are some restrictions on the valid directory structures:
  
          1. There can be only one vasp run in each directory. Nested directories
             are fine.
          2. Directories designated "relax1", "relax2" are considered to be 2
             parts of an aflow style run.
          3. Directories containing vasp output with ".relax1" and ".relax2" are
             also considered as 2 parts of an aflow style run.