code: func (session *Session) Close() {
  	for _, v := range session.stmtCache {
  		v.Close()
  	}
  
  	if session.db != nil {
  		// When Close be called, if session is a transaction and do not call
  		// Commit or Rollback, then call Rollback.
  		if session.tx != nil && !session.isCommitedOrRollbacked {
  			session.Rollback()
  		}
  		session.tx = nil
  		session.stmtCache = nil
  		session.db = nil
  	}
  }
docs: // Close release the connection from pool