code: def add_and_get(self, delta):
          '''
          Atomically adds `delta` to the current value.
  
          :param delta: The delta to add.
          '''
          with self._lock.exclusive:
              self._value += delta
              return self._valuf add_and_get(self, delta):
          '''
          Atomically adds `delta` to the current value.
  
          :param delta: The delta to add.
          '''
          with self._lock.exclusive:
              self._value += delta
              return self._value
docs: Atomically adds `delta` to the current value.
  
          :param delta: The delta to add.