The app uses 2 implimentations of concadenating function: RAM-depended and RAM-independent.
File gets 2 argumets as parameters. In the repo they're called "INPUT_A.csv" and "INPUT_B.csv". Both .csv files format should be defined as number-string. If numbers (which are the keys) are equal, the strings would be concadenated. Result is going to be in "result.csv".