sample_dag.py

Here's the enhanced version of your Airflow DAG code, following best practices:

```python
#!/usr/bin/env python3

"""
Airflow DAG: Sample Workflow
Generated from Markdown: sample.md
Generated: 2026-03-11 00:40:17

This workflow consists of 9 tools and 9 connections, processing a dataset from `US_Accidents_March23.csv`. The workflow includes a variety of tool types, including input/output tools, filter/decision tools, processing tools, and browse/display tools.
"""

import os
from datetime import datetime, timedelta
from airflow import DAG
from airflow.operators.python import PythonOperator

# Define default arguments for the DAG
default_args = {
    'owner': 'airflow',
    'depends_on_past': False,
    'email_on_failure': False,
    'email_on_retry': False,
    'retries': 1,
    'retry_delay': timedelta(minutes=5),
}

def validate_data_file(file_path):
    """
    Validate the file path for input data.

    Args:
        file_path (str): The file path to be validated.

    Returns:
        bool: True if the file is valid, False otherwise.
    """
    if not file_path.endswith(('.csv', '.xlsx', '.xls')):
        raise ValueError("Invalid file format. Only .csv, .xlsx, and .xls files are supported.")
    return True

def get_file_type(file_path):
    """
    Get the type of the file based on its extension.

    Args:
        file_path (str): The file path to determine the file type.

    Returns:
        str: The file type (e.g., csv, xlsx, xls).
    """
    if file_path.endswith('.csv'):
        return 'csv'
    elif file_path.endswith(('.xlsx', '.xls')):
        return 'excel'

def read_data_1(context):
    """
    Read input data from a CSV or Excel file.

    Args:
        context (dict): The DAG context containing the task ID and XCom key.

    Returns:
        int: The number of rows in the input data.
    """
    try:
        ti = context['ti']
        file_path = 'input.csv'
        
        # Validate the file path
        if not validate_data_file(file_path):
            raise ValueError("Invalid file format. Only .csv, .xlsx, and .xls files are supported.")
        
        # Read input data
        file_type = get_file_type(file