code: func (b *RWSetBuilder) AddToReadSet(ns string, key string, version *version.Height) {
  	nsPubRwBuilder := b.getOrCreateNsPubRwBuilder(ns)
  	nsPubRwBuilder.readMap[key] = NewKVRead(key, version)
  }
docs: // AddToReadSet adds a key and corresponding version to the read-set