You may add your own functions as well, inside the benchmark_functions.py file. For that, you have to first define your function like a regular one, then you must insert the function attributes inside the dictionary, as this dictionary is what the other files use for getting the required information about the functions.
NOTE: In the resulting animation gif, a small star symbol can be seen on a specific part of each function. This star shows the function's known minimum, and is used to check how PSO is performing. If the point is known, you may enter it in the functions dictionary (minimum_x and minimum_y keys), otherwise just assign None value to them.
Whichever function you want to see the optimization get performed on, you can simply assign the key number that is mapped to your expected function in the functions dictionary, inside the main.py file. You can use demonstrate function's file_path argument to specify where you want to save the output gif.