Replace hypen with dash in filenames

#!/usr/bin/env python3

import os
import sys

hypen = b'\xe2\x80\x93'.decode()
dash = '-'

def get_rename_pairs(root):
    results = []
    for root, dirs, files in os.walk(root):
        for file in files:
            if hypen in file:
                source = os.path.join(root, file)
                target = source.replace(hypen, dash)
                if not os.path.exists(target):
                    result = (source, target)
                    results.append(result)
    return results

if __name__ == '__main__':
    if len(sys.argv) != 2:
        print(sys.argv[0], 'top directory')
        sys.exit(1)
    pairs = get_rename_pairs(sys.argv[1])
    for pair in pairs:
        print('Renaming file {} to {}'.format(*pair))
        os.rename(*pair)