Format text with ansi sequences in powershell

AnsiEscapeFormat.ps1

# https://github.com/bozho/AnsiColorOut/blob/master/AnsiColorOut/Console.cs 
# https://stackoverflow.com/questions/4842424/list-of-ansi-color-escape-sequences

$esc=[char]0x001b

filter esc {
    param(
        [ValidateSet("underline","italic")]
        [string[]]$Format
    )
    $text = $PSItem
    $escSequence = "$esc["
    $Format|ForEach-Object -Process {
        switch($_) {
            "underline" {
                $escSequence += "4;"
            }
            "italic" {
                $escSequence += "3;"
            }
        }
    }
    "$($escSequence)m$([string]$text)$esc[0m" 
}