def put(self, key, value):
    '''Stores the object `value` named by `key`.

    Stores the object in the collection corresponding to ``key.path``.

    Args:
      key: Key naming `value`
      value: the object to store.
    '''
    if value is None:
      self.delete(key)
    else:
      self._collection(key)[key] = value
Stores the object `value` named by `key`.

    Stores the object in the collection corresponding to ``key.path``.

    Args:
      key: Key naming `value`
      value: the object to store.