hard solution

import os #to work with files and directorys
import json #to work with JSON
import csv #to work with CSV

#base class that store all data
class DataEntry(object):
    def __init__(self,date, time, sku, warehouse,
                 warehouse_cell_id, operation,invoice,
                 expiration_date,o  peration_cost,comment):
    #def __init__(self, *args):
        self.date = date
        self.time = time
        self.sku = sku
        self.warehouse = warehouse
        self.warehouse_cell_id = warehouse_cell_id
        self.operation = operation
        self.invoice = invoice
        self.expiration_date = expiration_date
        self.operation_cost = operation_cost
        self.comment = comment

    def to_string(self):
        return f'date: {self.date}\t ' \
               f'time: {self.time}\t ' \
               f'sku: {self.sku}\t ' \
               f'warehouse: {self.warehouse}\t ' \
               f'warehouse_cell_id: {self.warehouse_cell_id}\t ' \
               f'operation: {self.operation}\t ' \
               f'invoice: {self.invoice}\t ' \
               f'expiration_date: {self.expiration_date}\t ' \
               f'operation_cost: {self.operation_cost} ' \
               f'comment: {self.comment}'


class FileProcessor:
    def __init__(self, file_name):
        self.file = open(file_name)
        self.entrys = []

    def process_data(self):
        pass

    def show_entrys(self):
        for i in self.entrys:
            print(i.to_string())

class JSONFileProcessor(FileProcessor):
    def process_data(self):
        self.data = json.load(self.file)['data']
        for line in self.data:
            # create entry, giving to it list with values
            entry = DataEntry(*list(line.values()))
            # adding entry to list of class
            self.entrys.append(entry)
        return self.entrys

class CSVFileProcessor(FileProcessor):
    def process_data(self):
        self.data = csv.reader(self.file, delimiter=',', quotechar="\n")
        for line in self.data:
            # in first line are data titles, so we don't need it
            if self.data.line_num == 1:
                continue
            # create entry, giving to it list with values
            entry = DataEntry(*list(line))
            # adding entry to list of class
            self.entrys.append(entry)
        return self.entrys




# look all files in the same directory where current python file is
dir = os.getcwd()
processed_files = []
for i in os.listdir(dir):
    # if we found a dir just skip it
    if os.path.isdir(i): continue
    if i.endswith(".json"): # if we found a JSON file - process him
        j = JSONFileProcessor(i)
        j.process_data()
        processed_files.append(j)
    elif i.endswith(".csv"): # if we found a CSV file - process him
        c = CSVFileProcessor(i)
        c.process_data()
        processed_files.append(c)

for i in processed_files:
    i.show_entrys()
    print()