You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: revoke.go
    path of file: ./repos/cockroach/pkg/sql/sem/tree
    
    the code of the file until where you have to start completion: // Copyright 2012, Google Inc. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in licenses/BSD-vitess.txt.

// Portions of this file are additionally subject to the following
// license and copyright.
//
// Copyright 2015 The Cockroach Authors.
//
// Use of this software is governed by the Business Source Li
    
func (node *Revoke) Format(ctx *FmtCtx) {
	ctx.WriteString("REVOKE ")
	if node.Targets.System {
		ctx.WriteString(" SYSTEM ")
	}
	// NB: we cannot use FormatNode() here because node.Privileges is
	// not an AST node. This is OK, because a privilege list cannot
	// contain sensitive information.
	node.Privileges.FormatNames(&ctx.Buffer)
	if !node.Targets.System {
		ctx.WriteString(" ON ")
		ctx.FormatNode(&node.Targets)
	}
	ctx.WriteString(" FROM ")
	ctx.FormatNode(&node.Grantees)
}