How to use the pygubu.TkApplication function in pygubu

import argparse
try:
    import tkinter as tk
except:
    import Tkinter as tk

pygubu_basedir = os.path.abspath(os.path.dirname(
                    os.path.dirname(os.path.realpath(sys.argv[0]))))
if pygubu_basedir not in sys.path:
    sys.path.insert(0, pygubu_basedir)


from pygubu import Builder, TkApplication


class UITester(TkApplication):
    def __init__(self, uifile, rootwidget, rootmenu=None, master=None):
        self.uifile = uifile
        self.rootwidget = rootwidget
        self.rootmenu = rootmenu
        TkApplication.__init__(self, master)

    def _create_ui(self):
        self.builder = Builder()
        self.builder.add_from_file(self.uifile)
        self.builder.get_object(self.rootwidget, self.master)

        if self.rootmenu:
            menu = self.builder.get_object(self.rootmenu, top)
            self.set_menu(menu)

        #show callbacks defined

def __init__(self, uifile, rootwidget, rootmenu=None, master=None):
        self.uifile = uifile
        self.rootwidget = rootwidget
        self.rootmenu = rootmenu
        TkApplication.__init__(self, master)

# menu.py
try:
    import tkinter as tk
    from tkinter import messagebox
except:
    import Tkinter as tk
    import tkMessageBox as messagebox
import pygubu

class MyApplication(pygubu.TkApplication):

    def _create_ui(self):
        #1: Create a builder
        self.builder = builder = pygubu.Builder()

        #2: Load an ui file
        builder.add_from_file('menu.ui')

        #3: Create the widget using self.master as parent
        self.mainwindow = builder.get_object('mainwindow', self.master)

        # Set main menu
        self.mainmenu = menu = builder.get_object('mainmenu', self.master)
        self.set_menu(menu)

        # Configure callbacks

# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTIBILITY
# or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
# for more details.

import tkinter as tk
import pygubu
from selenium import webdriver
from pyutil import Util
from pyutil import Mail
from pyutil import LibO
from pyutil import CFDIPDF
from values import Global


class Application(pygubu.TkApplication):

    def __init__(self, parent):
        self.parent = parent
        self.util = Util()
        self.g = Global()
        self._init_var()
        self._create_ui()

    def _init_var(self):
        self.builder = pygubu.Builder()
        self.config = self.util.load_config(self.g.FILES['config'])
        self.users_sat = {}
        self.mail_servers = {}
        self.users_xml = {}
        self.users_pdf = {}
        self.users_report = {}

txtcolor = 'black'
            self.tklabel.configure(text=msg, foreground=txtcolor)
        except (KeyboardInterrupt, SystemExit):
            raise
        except:
            self.handleError(record)

    def clear(self):
        self.tklabel.configure(text='', foreground='black')
        self._clear = True


FILE_PATH = os.path.dirname(os.path.abspath(__file__))


class PygubuUI(pygubu.TkApplication):
    """Main gui class"""

    def _init_before(self):
        init_pygubu_widgets()

    def _create_ui(self):
        """Creates all gui widgets"""

        self.preview = None
        self.about_dialog = None
        self.preferences = None
        self.builder = pygubu.Builder(translator)
        self.currentfile = None
        self.is_changed = False

        uifile = os.path.join(FILE_PATH, "ui/pygubu-ui.ui")