Why have the options to define the single and double blocks_to_swap been removed?

Any model with a different block count can only inefficiently make use of this option:

--double_blocks_to_swap and --single_blocks_to_swap are deprecated. These options is still available, but they will be removed in the future. Please use --blocks_to_swap instead. These options are equivalent to specifying double_blocks_to_swap + single_blocks_to_swap // 2 in --blocks_to_swap.

Cannot swap more than 6 double blocks and 36 single blocks. Requested 18 double blocks and 36 single blocks.

i manually edited the flux_models.py so i can actually swap the blocks, but it would still be nice if we could define single and double blocks manually.

Start in flux_models.py and trace how --blocks_to_swap is converted into double- and single-block limits. Compare that path with the deprecated --double_blocks_to_swap and --single_blocks_to_swap options, then check whether existing tests cover these arguments. Done means users can set the two block counts manually and the requested counts are validated correctly.

Written by the indexing model from the issue text.