function Find-MergedGitBranches {
    [CmdletBinding()]
    param ()

    $alwaysKeep = @('main','master','develop','release')

    $mergedLines = Invoke-GitCommand -Verb branch -Arguments @("--merged")

    $branches = @()

    foreach ($line in $mergedLines) {
        $trimLine = $line.Trim()
        if ($trimLine.StartsWith("*") -or $alwaysKeep -contains $trimLine) {
            continue
        } else {
            $branches += $trimLine
        }
    }

    # Look for branches removed on origin
    $goneLines = Invoke-GitCommand -Verb branch -Arguments @("-vv")

    foreach ($line in $goneLines) {
        if ($line -match 'gone') {
            # magic string split
            $line = ($line -split '\[')[0]

            # Remove the committish at the end of the line
            $line = $line.Substring(0, $_.Length - 9)
            $trimLine = $line.Trim()
            if ($trimLine.StartsWith("*") -or $alwaysKeep -contains $trimLine) {
                continue
            } else {
                $branches += $trimLine
            }
        }
    }

    return $branches
}