code: def cli(env, sortby, columns, datacenter, username, storage_type):
      
      block_manager = SoftLayer.BlockStorageManager(env.client)
      block_volumes = block_manager.list_block_volumes(datacenter=datacenter,
                                                       username=username,
                                                       storage_type=storage_type,
                                                       mask=columns.mask())
  
      table = formatting.Table(columns.columns)
      table.sortby = sortby
  
      for block_volume in block_volumes:
          table.add_row([value or formatting.blank()
                         for value in columns.row(block_volume)])
  
      env.fout(table)
docs: List block storage.