Test-IsWindows.ps1

function Test-IsWindows
{
  <#
      .SYNOPSIS
      Returns $true when run on Windows, else $false
 
      .DESCRIPTION
      Variables like $isWindows were introduced in PowerShell 7 but are missing in Windows PowerShell.
      This function provides a uniform way of finding out whether the script runs on Windows or another operating system.
 
      .EXAMPLE
      Test-IsWindows
      returns $true when executed on Windows, else $false
  #>



  if ($PSVersionTable['PSVersion'].Major -le 5)
  { $true }
  else
  {
    $isWindows
  }
}