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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def cli(env):
 """List placement groups."""

    manager = PlacementManager(env.client)
    result = manager.list()
    table = formatting.Table(
        ["Id", "Name", "Backend Router", "Rule", "Guests", "Created"],
        title="Placement Groups"
    )
    for group in result:
        table.add_row([
            group['id'],
            group['name'],
            group['backendRouter']['hostname'],
            group['rule']['name'],
            group['guestCount'],
            group['createDate']
        ])

    env.fout(table)