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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, volume_id, replicant_id):
 """Failback a block volume from the given replicant volume."""

    block_storage_manager = SoftLayer.BlockStorageManager(env.client)

    success = block_storage_manager.failback_from_replicant(
        volume_id,
        replicant_id
    )

    if success:
        click.echo("Failback from replicant is now in progress.")
    else:
        click.echo("Failback operation could not be initiated.")