Write a program for simple ETL(Extraction, Transformation and Loading) Implementation, the output does not matter, your coding approach matter. The scenario is, read file(s) for one directory, perform some transformation on the data and write it to another directory. They emphasize on what you do if the source and destination is changed to something else like SQL DB and you can add more transformations to the program. They want all the component to be independent and some insane design implementation on injecting transformation side.