Delilah critiques a Python script she found in her workplace. The script attempts to merge YAML data, effectively updating old configurations with new ones. A major problem is the function key_exists, which needlessly recreates Python's built-in in operator. This function uses try-except blocks, a clumsy approach compared to the simple key in dictionary idiom. The script's author inconsistently uses both the correct in operator and the flawed key_exists function within the same code. The code's overall structure is messy, resembling poorly written shell scripting. The script reads and loads YAML files using yaml.load and then merges the data. It contains a revert_db_tags function meant for handling database tag updates. The core logic involves comparing keys and values between the old and new YAML data. The comparisons trigger merging or specific tag adjustments to the new data. Finally, the modified data is written back to the new YAML file using yaml.dump. The author concludes that the script is poorly written and demonstrates an unnecessary complication of Python's built-in functionalities.