code: func (b *BlockChain) ThresholdState(deploymentID uint32) (ThresholdState, error) {
  	b.chainLock.Lock()
  	state, err := b.deploymentState(b.bestChain.Tip(), deploymentID)
  	b.chainLock.Unlock()
  
  	return state, err
  }
docs: // ThresholdState returns the current rule change threshold state of the given
  // deployment ID for the block AFTER the end of the current best chain.
  //
  // This function is safe for concurrent access.