git ls-files | ForEach-Object {
    $extension = [System.IO.Path]::GetExtension($_)
    $lineCount = (Get-Content $_ | Measure-Object -Line).Lines
    [PSCustomObject]@{
        Extension = $extension
        LineCount = $lineCount
    }
} | Group-Object Extension | ForEach-Object {
    [PSCustomObject]@{
        Extension = $_.Name
        TotalLineCount = ($_.Group | Measure-Object LineCount -Sum).Sum
    }
} | Sort-Object Extension