class_docstr: Dictionary populated on first use.
class_docstr_tok: ["Dictionary","populated","on","first","use","."]
code: def keys(self):
      if self.data is None:
          _fill_lock.acquire()
          try:
              if self.data is None:
                  self._fill()
          finally:
              _fill_lock.release()
      return self.data.keys()
  
file_path: catboost/contrib/python/pytz/py2/pytz/lazy.py
imports: from threading import RLock
label_desc: Use image node_id 5 for calling the LazyDict obj's underlying member method code with example usage: obj.keys() and returns: self