Git Remove Branches Merged Upstream

gistfile1.txt

function Git-RemoveBranchesMergedUpStream {
     git fetch -p |  git remote prune origin | git branch -vv | 
     select-string ": gone]" |  
     ForEach-Object { $_.Line.Substring(2, $_.Line.IndexOf(' ', 2))  } |  
     ForEach-Object { git branch -d $_ }
}