$wsl_state = (Get-WindowsOptionalFeature -Online -FeatureName Microsoft-Windows-Subsystem-Linux).State
if ($wsl_state) {
  Write-Output "WSL has already been enabled."
  exit(0)
}
if ($wsl_state -eq $null) {
  Write-Output "WSL cannot be enabled because it doesn't exist on your PC.  Update it to the latest Windows 10."
  exit(1)
}
Enable-WindowsOptionalFeature -Online -FeatureName Microsoft-Windows-Subsystem-Linux