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: set_iam_policy.go
    path of file: ./repos/golang-samples/datacatalog/snippets/policytagmanager
    
    the code of the file until where you have to start completion: // Copyright 2020 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package policytagmanager

// [START data_catalog_ptm_set_iam_policy]
import (
	"context"
	"fmt"
	"io"

	datacatalog "cloud.google.com/go/datacatalog/apiv1beta1"
	iampb "google.golang.org/genproto/googleapis/iam/v1"
)

// setIAMPolicy demonstrates altering the policy of a given taxonomy or policy
// tag resource.  In this example, we append a binding to the existing policy
// to add the fine grained reader role to a specific member.
func setIAMPolicy(w io.Writer, resourceID, member string) error {
	// resou
    
func setIAMPolicy(w io.Writer, resourceID, member string) error {
	// resourceID := "projects/myproject/locations/us/taxonomies/1234/policyTags/5678"
	// member := "group:my-trusted-group@example.com"
	ctx := context.Background()
	policyClient, err := datacatalog.NewPolicyTagManagerClient(ctx)
	if err != nil {
		return fmt.Errorf("datacatalog.NewPolicyTagManagerClient: %w", err)
	}
	defer policyClient.Close()

	// First, retrieve the existing policy.
	req := &iampb.GetIamPolicyRequest{
		Resource: resourceID,
		Options: &iampb.GetPolicyOptions{
			RequestedPolicyVersion: 3,
		},
	}
	policy, err := policyClient.GetIamPolicy(ctx, req)
	if err != nil {
		return fmt.Errorf("GetIamPolicy: %w", err)
	}

	// Alter the policy to add an additional binding.
	newPolicy := policy
	newPolicy.Bindings = append(newPolicy.Bindings, &iampb.Binding{
		Role:    "roles/datacatalog.categoryFineGrainedReader",
		Members: []string{member},
	})

	sReq := &iampb.SetIamPolicyRequest{
		Resource: resourceID,
		Policy:   newPolicy,
	}
	updatedPolicy, err := policyClient.SetIamPolicy(ctx, sReq)
	if err != nil {
		return fmt.Errorf("SetIamPolicy: %w", err)
	}
	fmt.Fprintf(w, "set policy on resource %s with Etag %x\n", resourceID, updatedPolicy.Etag)
	return nil
}