{P : Sort u} →
  {username : String} →
    {uid gid : Option UInt64} →
      {shell homedir : Option String} →
        {username' : String} →
          {uid' gid' : Option UInt64} →
            {shell' homedir' : Option String} →
              { username := username, uid := uid, gid := gid, shell := shell, homedir := homedir } =
                  { username := username', uid := uid', gid := gid', shell := shell', homedir := homedir' } →
                (username = username' → uid = uid' → gid = gid' → shell = shell' → homedir = homedir' → P) → P