TypeError: can only concatenate str (not "tuple") to str :     def main():
    chatbot = ChatBot('Bot',
                      storage_adapter ='chatterbot.storage.SQLStorageAdapter',
                      trainer = 'chatterbot.trainers.ListTrainer')
    for files in os.listdir('hector/'):
        convData = open(r'hector/' + files, encoding='latin-1').readlines()
        #convData = open('hector/' + files, 'r').readlines()
        chatbot.set_trainer(ListTrainer)
        chatbot.train(convData)
main()

on this hector folder have trainnig text folders,when use os.listdir it's showing this error
IsADirectoryError: [Errno 21] Is a directory: 'hector/french'