Function calling using class() not working when used to add video files with mkvmerge, FFmpeg

import subprocess
filename = input('file name: ')
track1 = input('file name: ')
track2 = input('file name: ')
outputfile = input('file name: ')


class trial:

    #constructor of trial class
    def __init__(self):
        self.filename =filename
        self.track1 =track1
        self.track2 =track2
        self.outputfile =outputfile

    def mkvmerge(self):
        self.commandlist = [
            "mkvmerge",
            "-o",
            self.outputfile,
            self.track1,
            self.track2,
            self.filename

            ]
        return

    def runmkvmerge(self):
        self.mkvmerge()
        print(self.commandlist)

object = trial()
object.runmkvmerge()

//I learned about the init and class() so I used that to write this code but although it shows no error the script does not work. I am trying to add audio files to a video file using mkvmerge and the command is very simple but strangely it does not work//