Update multiple Windows Server 2016 TP4+ Nano Servers remotely using CIM

Update-Nano-Servers-using-Cim.ps1

function Get-AvailableUpdates {
    [CmdletBinding()]
    param (
        [PSCredential] $Credential = (Get-Credential -Message 'Credentials to use to update Servers'),

        [Parameter(Mandatory)]
        [ValidateNotNullOrEmpty()]
        [String[]] $Servers,

        [Switch] $Install,
        
        [Switch] $Restart
    )
    $servers | foreach-object {
        $session = New-CimSession `
            -ComputerName $_ `
            -Credential $credential
        $instance =  New-CimInstance `
            -Namespace root/Microsoft/Windows/WindowsUpdate `
            -ClassName MSFT_WUOperationsSession `
            -CimSession $session
        # Due to a bug in CIM on Nano Server (TP4 and TP5) an error is returned when
        # there are no available updates.
        # We use ErrorAction SilentlyContinue to ignore this (DON'T do this in a production script!!!!)
        $scanResults = @($Instance | Invoke-CimMethod `
            -MethodName ScanForUpdates `
            -Arguments @{SearchCriteria="IsInstalled=0";OnlineScan=$true} `
            -CimSession $session `
            -errorAction SilentlyContinue)
        if ($scanResults)
        {
            "$_ has $($scanResults.Count) updates to be installed:"
            if ($install)
            {
                $installResult = $Instance | Invoke-CimMethod `
                    -MethodName ApplyApplicableUpdates `
                    -CimSession $Session
                if ($installResult.ReturnValue -eq 0)
                {
                    'Updates were installed successfully:'
                    $scanResults.Updates
                    if ($Restart)
                    {
                        "Restarting $_"
                        Invoke-Command `
                            -ComputerName $_ `
                            -Credential $credential `
                            -ScriptBlock { Restart-Computer }
                    }
                    else
                    {
                        'You may need to reboot this server for update installation to complete.'
                    }
                }
                else
                {
                    'An error occurred installing updates:'
                    $installResult
                }
            }
            else
            {
                'Set -Install flag to install updates'
                $scanResults.Updates
            } # if
        }
        else
        {
            "$_ has no updates to be installed."
        } # if
        Remove-CimSession `
            -CimSession $session
    } # foreach-object
} # function Get-AvailableUpdates