code: func (adapter *Encoder) SetIndent(prefix, indent string) {
  	config := adapter.stream.cfg.configBeforeFrozen
  	config.IndentionStep = len(indent)
  	adapter.stream.cfg = config.frozeWithCacheReuse(adapter.stream.cfg.extraExtensions)
  }
docs: // SetIndent set the indention. Prefix is not supported