No module named 'block_sparse_attn'

from block_sparse_attn import block_sparse_attn_func

File "/home/zxy/project/FlashVSR/examples/WanVSR/infer_flashvsr_tiny.py", line 12, in
from diffsynth import ModelManager, FlashVSRTinyPipeline
File "/home/zxy/project/FlashVSR/diffsynth/init.py", line 2, in
from .models import *
File "/home/zxy/project/FlashVSR/diffsynth/models/init.py", line 1, in
from .model_manager import *
File "/home/zxy/project/FlashVSR/diffsynth/models/model_manager.py", line 4, in
from .downloader import download_models, download_customized_models, Preset_model_id, Preset_model_website
File "/home/zxy/project/FlashVSR/diffsynth/models/downloader.py", line 6, in
from ..configs.model_config import preset_models_on_huggingface, preset_models_on_modelscope, Preset_model_id
File "/home/zxy/project/FlashVSR/diffsynth/configs/model_config.py", line 58, in
from ..models.wan_video_dit import WanModel
File "/home/zxy/project/FlashVSR/diffsynth/models/wan_video_dit.py", line 30, in
from block_sparse_attn import block_sparse_attn_func
ModuleNotFoundError: No module named 'block_sparse_attn'

Start with examples/WanVSR/infer_flashvsr_tiny.py and diffsynth/models/wan_video_dit.py, where the missing import is reached. Check the repository's setup and dependency instructions for how block_sparse_attn is expected to be provided, then rerun the example. Done means the import succeeds and this ModuleNotFoundError no longer blocks startup.