code: func (c *Cluster) GetRegion(regionID uint64) (*metapb.Region, uint64) {
  	c.RLock()
  	defer c.RUnlock()
  
  	r := c.regions[regionID]
  	if r == nil {
  		return nil, 0
  	}
  	return proto.Clone(r.Meta).(*metapb.Region), r.leader
  }
docs: // GetRegion returns a Region's meta and leader ID.