FFprobe command showing no output result

import subprocess 
filename = input('name of the file: ')     
class trial:

    def __init__(self):
        self.filename =filename

    def buildFFprobe(self):
        self.commandlist = ["ffprobe", "show_entries", 
        "stream=codec_type", "start_time", "- v", "-of", 
        "compact=p=1:nk=0", self.filename]
    
        return

    def runFFprobe(self):
        self.buildFFprobe()
        print(self.commandlist)

object = trial()
object.runFFprobe()

// I have corrected the initial code with 'self.filename' to self.filename now it prints the commandlist with proper input file. But it fails me why no output result is generated. A review of the code is appreciated if anybody got the time. //