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: create_deny_policy.go
    path of file: ./repos/golang-samples/iam/deny
    
    the code of the file until where you have to start completion: // Copyright 2022 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in comp
    
func createDenyPolicy(w io.Writer, projectID, policyID string) error {
	// You can add deny policies to organizations, folders, and projects.
	// Each of these resources can have up to 5 deny policies.
	// Deny policies contain deny rules, which specify the following:
	// 1. The permissions to deny and/or exempt.
	// 2. The principals that are denied, or exempted from denial.
	// 3. An optional condition on when to enforce the deny rules.

	// projectID := "your_project_id"
	// policyID := "your_policy_id"

	ctx := context.Background()
	policiesClient, err := iam.NewPoliciesClient(ctx)
	if err != nil {
		return fmt.Errorf("NewPoliciesClient: %w", err)
	}
	defer policiesClient.Close()

	// Each deny policy is attached to an organization, folder, or project.
	// To work with deny policies, specify the attachment point.
	//
	// Its format can be one of the following:
	// 1. cloudresourcemanager.googleapis.com/organizations/ORG_ID
	// 2. cloudresourcemanager.googleapis.com/folders/FOLDER_ID
	// 3. cloudresourcemanager.googleapis.com/projects/PROJECT_ID
	//
	// The attachment point is identified by its URL-encoded resource name. Hence, replace
	// the "/" with "%%2F".
	attachmentPoint := fmt.Sprintf(
		"cloudresourcemanager.googleapis.com%%2Fprojects%%2F%s",
		projectID,
	)

	denyRule := &iampb.DenyRule{
		// Add one or more principals who should be denied the permissions specified in this rule.
		// For more information on allowed values,
		// see: https://cloud.google.com/iam/help/deny/principal-identifiers
		DeniedPrincipals: []string{"principalSet://goog/public:all"},
		// Optionally, set the principals who should be exempted from the
		// list of denied principals. For example, if you want to deny certain permissions
		// to a group but exempt a few principals, then add those here.
		// ExceptionPrincipals: []string{"principalSet://goog/group/project-admins@example.com"},
		//
		// Set the permissions to deny.
		// The permission value is of the format: service_fqdn/resource.action
		// For the list of supported permissions,
		// see: https://cloud.google.com/iam/help/deny/supported-permissions
		DeniedPermissions: []string{"cloudresourcemanager.googleapis.com/projects.delete"},
		// Optionally, add the permissions to be exempted from this rule.
		// Meaning, the deny rule will not be applicable to these permissions.
		// ExceptionPermissions: []string{"cloudresourcemanager.googleapis.com/projects.create"},
		//
		// Set the condition which will enforce the deny rule.
		// If this condition is true, the deny rule will be applicable.
		// Else, the rule will not be enforced.
		// The expression uses Common Expression Language syntax (CEL).
		// Here we block access based on tags.
		//
		// Here, we create a deny rule that denies the
		// cloudresourcemanager.googleapis.com/projects.delete permission
		// to everyone except project-admins@example.com for resources that are tagged test.
		// A tag is a key-value pair that can be attached to an organization, folder, or project.
		// For more info, see: https://cloud.google.com/iam/docs/deny-access#create-deny-policy
		DenialCondition: &expr.Expr{
			Expression: "!resource.matchTag('12345678/env', 'test')",
		},
	}

	// Add the deny rule and a description for it.
	policyRule := &iampb.PolicyRule{
		Description: "block all principals from deleting projects, unless the principal is a member of project-admins@example.com and the project being deleted has a tag with the value test",
		Kind: &iampb.PolicyRule_DenyRule{
			DenyRule: denyRule,
		},
	}

	policy := &iampb.Policy{
		DisplayName: "Restrict project deletion access",
		Rules:       [](*iampb.PolicyRule){policyRule},
	}

	req := &iampb.CreatePolicyRequest{
		// Construct the full path of the resource's deny policies.
		// Its format is: "policies/ATTACHMENT_POINT/denypolicies"
		Parent:   fmt.Sprintf("policies/%s/denypolicies", attachmentPoint),
		Policy:   policy,
		PolicyId: policyID,
	}
	op, err := policiesClient.CreatePolicy(ctx, req)
	if err != nil {
		return fmt.Errorf("unable to create policy: %w", err)
	}

	policy, err = op.Wait(ctx)
	if err != nil {
		return fmt.Errorf("unable to wait for the operation: %w", err)
	}

	fmt.Fprintf(w, "Policy %s created\n", policy.GetName())

	return nil
}