internal/functions/Get-ComputerName.ps1

function Get-ComputerName {
    if ($null -ne $computername) {
        return $computername
    }
    else {
        $computers = Get-DbcConfigValue app.computername
        if ($computers.Count -eq 0) {
            Write-PSFMessage -Level Warning -Message "You must specify -ComputerName or use Set-DbcConfig app.computername to setup a list of servers"
        }
        else {
            $computers
        }
    }
}