from openpyxl.reader.excel import load_workbook


wb2 = load_workbook(filename = 'sebes.xlsx')
wb3 = load_workbook(filename = 'ishod.xlsx')
ws2 = wb2.active
ws3 = wb3.active

def find_sebes(arg):
    slovar = dict(arg)
    for row in ws3.values:
        shtrih = str(row[0])
        sebes = slovar.get(shtrih)
        if sebes:
            print(shtrih, sebes)


def create_list():
    data = []
    for row in ws2.values:
        shtrih = str(row[0])
        sebes = row[6]
        data.append((shtrih, sebes))
    return data


def show_list(arg):
    print(dict(arg).get('5900516303105')) # 345 expected


find_sebes(create_list())

wb2.close()
wb3.close()