code: func (p *Parser) parseKillQueryStatement() (*KillQueryStatement, error) {
  	qid, err := p.ParseUInt64()
  	if err != nil {
  		return nil, err
  	}
  
  	var host string
  	if tok, _, _ := p.ScanIgnoreWhitespace(); tok == ON {
  		host, err = p.ParseIdent()
  		if err != nil {
  			return nil, err
  		}
  	} else {
  		p.Unscan()
  	}
  	return &KillQueryStatement{QueryID: qid, Host: host}, nil
  }
docs: // parseKillQueryStatement parses a string and returns a kill statement.
  // This function assumes the KILL token has already been consumed.