def sub_grid_size_tag_from_sub_grid_size(sub_grid_size):
return '<STR_LIT>' + str(sub_grid_size)<EOL>
Generate a sub-grid tag, to customize phase names based on the sub-grid size used.

    This changes the phase name 'phase_name' as follows:

    sub_grid_size = None -> phase_name
    sub_grid_size = 1 -> phase_name_sub_grid_size_2
    sub_grid_size = 4 -> phase_name_sub_grid_size_4