```python
from athenaidx.config import Config
from athenaidx.workflows.base_workflow import WorkflowContext
from athenaidx.workflows.post_line_item_rejections import PostLineItemRejections
import pandas as pd

sample_data = pd.read_csv(file_path)

# convert sample_data into RejectionGrouped objects as needed
from athenaidx.model_objects.rejections import RejectionGrouped, Rejections
rejections = Rejections.from_dataframe(sample_data)

rejections_grouped = RejectionGrouped.group_by_group_num(rejections)

cfg = Config()
ctx = WorkflowContext(config=cfg, data=rejections_grouped)
wf = PostLineItemRejections(ctx)
wf.run()

```