'Initialization of the parallel exec + concat (Tower).
Args:
block_list: List of blocks.BlockBase that are chained to create
a new blocks.BlockBase.
dim: the dimension on which to concat.
name: Name of this block.'

def __init__(self, block_list, dim=3, name=None):

    super(TowerOperator, self).__init__(name)
    self._blocks = block_list
    self._concat_dim = dim
