import tensorflow as tf

        input_use_counts = [0] * len(cell_inputs + blocks)
        for (idx1, _, idx2, _) in cell_arch:
            input_use_counts[idx1] += 1
            input_use_counts[idx2] += 1

        # Concat only unused blocks
        with tf.variable_scope('combine'):
            block_use_counts = input_use_counts[len(cell_inputs):]
            out_blocks = [block for (block, use_count) in zip(blocks, block_use_counts) if use_count == 0]
            comb_ch = len(out_blocks) * block_ch
            X = tf.concat(out_blocks, axis=3)

