#!/usr/bin/env python3
"""
A simple command line tool that greets the user.
"""

import argparse
import sys


def main():
    """Main function to handle command line arguments and greet the user."""
    parser = argparse.ArgumentParser(
        description='A simple greeting tool',
        epilog='Example: halo "World"'
    )
    
    parser.add_argument(
        'name',
        nargs='?',  # Makes the argument optional
        help='The name or thing to greet',
        default=None
    )
    
    parser.add_argument(
        '-v', '--version',
        action='version',
        version='halo 1.0.0'
    )
    
    args = parser.parse_args()
    
    # If no name provided, ask for input
    if args.name is None:
        try:
            name = input('Enter something: ')
        except KeyboardInterrupt:
            print("\nGoodbye!")
            sys.exit(0)
    else:
        name = args.name
    
    # Print the greeting
    print(f'hello {name}')


if __name__ == '__main__':
    main()
