Python Batch Rename Files

import os
path="F:\\path_to_modify\\"
for file in os.listdir(path):
    if os.path.isfile(os.path.join(path,file)):
        new_name=file.replace("OLD_SUBSTRING","NEW_SUBSTRING")
        os.rename(os.path.join(path,file),os.path.join(path,new_name))
print ("complete!")