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: node_module_expand.go
    path of file: ./repos/terraform/internal/terraform
    
    the code of the file until where you have to start completion: // Copyright (c) HashiCorp, Inc.
// SPDX-License-Identifier: BUSL-1.1

package terraform

import (
	"log"

	"github.com/hashicorp/terraform/internal/addrs"
	"github.com/hashicorp/terraform/internal/configs"
	"github.com/hashicorp/terraform/internal/dag"
	"github.com/hashicorp/terraform/internal/experiments"
	"github.com/hashicorp/terraform/internal/lang"
	"github.com/hashicorp/terraform/internal/tfdiags"
)

type ConcreteModuleNodeFunc func(n *nodeExpandModule) dag.Vertex

// nodeExpandModule represents a module call in the configuration that
// might expand into multiple module instances depending on how it is
// configured.
type nodeExpandModule struct {
	Addr       addrs.Module
	Config     *configs.Module
	ModuleCall *configs.ModuleCall
}

var (
	_ GraphNodeExecutable       = (*nodeExpandModule)(nil)
	_ GraphNodeReferencer       = (*nodeExpandModule)(nil)
	_ GraphNodeReferenceOutside = (*nodeExpandModule)(nil)
	_ graphNodeExpandsInstances = (*nodeExpand
    
func (n *nodeValidateModule) Execute(globalCtx EvalContext, op walkOperation) (diags tfdiags.Diagnostics) {
	_, call := n.Addr.Call()
	expander := globalCtx.InstanceExpander()

	// Modules all evaluate to single instances during validation, only to
	// create a proper context within which to evaluate. All parent modules
	// will be a single instance, but still get our address in the expected
	// manner anyway to ensure they've been registered correctly.
	for _, module := range expander.ExpandModule(n.Addr.Parent()) {
		moduleCtx := evalContextForModuleInstance(globalCtx, module)

		// Validate our for_each and count expressions at a basic level
		// We skip validation on known, because there will be unknown values before
		// a full expansion, presuming these errors will be caught in later steps
		switch {
		case n.ModuleCall.Count != nil:
			_, countDiags := evaluateCountExpressionValue(n.ModuleCall.Count, moduleCtx)
			diags = diags.Append(countDiags)

		case n.ModuleCall.ForEach != nil:
			forEachDiags := newForEachEvaluator(n.ModuleCall.ForEach, moduleCtx, false).ValidateResourceValue()
			diags = diags.Append(forEachDiags)
		}

		diags = diags.Append(validateDependsOn(moduleCtx, n.ModuleCall.DependsOn))

		// now set our own mode to single
		expander.SetModuleSingle(module, call)
	}

	return diags
}