How to call the child window using parent method in tkinter? Can anyone help me please.

gistfile1.txt

import tkinter as tk
import tkMessageBox
import ttk


class Track(tk.Frame):
    def __init__(self, master):
        tk.Frame.__init__(self, master)
        x = (self.master.winfo_screenwidth() - self.master.winfo_reqwidth()) / 2
        y = (self.master.winfo_screenheight() - self.master.winfo_reqheight()) / 2
        self.master.geometry("+{}+{}".format(x, y))
        self.pack()
        self.master.resizable(False, False)
        self.master.title("Sample")
        self.main_container()


    def main_container(self):
    
        tk.Message(self, text = "Person", font = 'arial 20 bold', justify = 'center', aspect = 800 ).pack(pady = (15, 0), side = 'top') 
        dialog_frame = tk.Frame(self, relief = 'raise', bg = 'lightgrey', height = 100, bd = 10)
        dialog_frame.pack(padx = 10, pady = 5, anchor = 'w')
        
        tk.Label(dialog_frame, text = "Name: ", bg = 'lightgrey', font = 'arial 13').grid(row = 0, column = 0, sticky = 'w')
        self.name = tk.Entry(dialog_frame, fg = 'black',font = 'arial 13', width = 25, bd = 3, relief = "sunken")
        self.name.grid(row = 0, column = 1, sticky = 'w')
    
        tk.Label(dialog_frame, bg = 'lightgrey', text = "Address: " , font = 'arial 13').grid(row = 1, column = 0, sticky = 'w')
        self.address = tk.Entry(dialog_frame, fg = 'black',font = 'arial 13', width = 25, bd = 3, relief = "sunken")
        self.address.grid(row = 1, column = 1, sticky = 'w')

        tk.Label(dialog_frame,  bg = 'lightgrey', text = "Gender: ", font = 'arial 13').grid(row = 2, column = 0, sticky = 'w')
        self.check1 = tk.Checkbutton(dialog_frame, text = 'Male', bg = 'lightgrey', onvalue = 1,font = 'arial 13', offvalue = 0, height = 1, width = 5, cursor = 'sizing', activebackground = 'lightgreen')
        self.check1.grid(row = 2, column = 1, sticky = 'w')
        self.check1 = tk.Checkbutton(dialog_frame, text = 'Female', bg = 'lightgrey', font = 'arial 13', onvalue = 1, offvalue = 0, height = 1, width = 5, cursor = 'heart', activebackground = 'pink')
        self.check1.grid(row = 2, column = 1, sticky = 'e')

        tk.Label(dialog_frame, text = "Contact #: " , bg = 'lightgrey',  font = 'arial 13').grid(row = 3, column = 0, sticky = 'w')
        self.contact = tk.Entry(dialog_frame, fg = 'black', width = 25,bd = 3, relief = "sunken", font = 'arial 13')
        self.contact.grid(row = 3, column = 1, sticky = 'w')

        tk.Label(dialog_frame, text = "Track:", bg = 'lightgrey', font = 'arial 13').grid(row = 4, column = 0, sticky = 'w') 
        self.chooser = ttk.Combobox(dialog_frame,width = 25)
        self.chooser['values'] = ("Faculty", "Staff", "Student")
        self.chooser.grid(row = 4, column = 1, sticky = 'w')
        
#------------------------------- Botton Frame --------------------------
        button_frame = tk.Frame(self)
        button_frame.pack(padx = 10, pady = 1, anchor = 'n')

        self.buttonSave = tk.Button(button_frame, text = 'save',font = 'arial 13', activebackground = 'green', cursor = 'cross',bd = 3, command = self.error, relief = "raised")
        self.buttonSave.grid(row = 0, column = 1, sticky = 'w')
        self.buttonCancel = tk.Button(button_frame, text = 'cancel',font = 'arial 13', activebackground = 'red', cursor = 'circle',bd = 3, command = self.clickcancel, relief = "raised")
        self.buttonCancel.grid(row = 0, column = 2, sticky = 'e')

#------------------------------------ Methods --------------------------


#--------------------------------- Destroy Function -----------------------       

    def clickcancel(self):
        self.master.destroy()
        
#------------------------------------ Error Function --------------------------
        
    def error(self):
        if self.chooser.get() == '' or self.name.get() == '' or self.address.get() == '' or self.contact.get() == '':
            tkMessageBox.showwarning("Incomplete", "Please fill all the Availabe Fields")
        else:
            return self.cont()

    def save(self):
        if self.entry1.get() == '' or self.entry2.get() == '':
            tkMessageBox.showwarning("Incomplete", "Please fill all the Availabe Fields")
        else:
            tkMessageBox.showinfo("Succes", "Register Complete!")
            self.master.destroy()
            
#------------------------------------ Filter Function --------------------------       
    def cont(self):
        self.grabstud = Student()
	self.grabfac = Faculty()
	self.grabstaff = Staff()
        
        if self.chooser.get() == "Faculty":
            return self.grabfac()
	elif self.chooser.get() == "Student":
            return self.grabstud()
	elif self.chooser.get() == "Staff":
            return self.grabstaff()

        

class Student(Track):
    
    def __init__(self, master):
        super().__init__(master)
        self.student_container()

    def student_container(self):
        self.master.title("Student Program")
        tk.Message(self, text = "Student", font = 'arial 20 bold', justify = 'center', aspect = 800 ).pack(pady = (15, 0), side = 'top') 
        dialog_frame = tk.Frame(self, relief = 'raise', bg = 'lightgrey', height = 100, bd = 10)
        dialog_frame.pack(padx = 10, pady = 5, anchor = 'w')
        
        tk.Label(dialog_frame, text = "Course: ", bg = 'lightgrey', font = 'arial 13').grid(row = 0, column = 0, sticky = 'w')
        self.entry1 = tk.Entry(dialog_frame, fg = 'black',font = 'arial 13', width = 25, bd = 3, relief = "sunken")
        self.entry1.grid(row = 0, column = 1, sticky = 'w')
    
        tk.Label(dialog_frame, bg = 'lightgrey', text = "Major: " , font = 'arial 13').grid(row = 1, column = 0, sticky = 'w')
        self.entry2 = tk.Entry(dialog_frame, fg = 'black',font = 'arial 13', width = 25, bd = 3, relief = "sunken")
        self.entry2.grid(row = 1, column = 1, sticky = 'w')

        button_frame = tk.Frame(self)
        button_frame.pack(padx = 10, pady = 1, anchor = 'n')

        self.buttonSave = tk.Button(button_frame, text = 'Save',font = 'arial 13', activebackground = 'green', cursor = 'cross', command = self.save, relief = "raised")
        self.buttonSave.grid(row = 0, column = 1, sticky = 'w')
        self.buttonCancel = tk.Button(button_frame, text = 'Cancel',font = 'arial 13', activebackground = 'red', cursor = 'circle', command = self.cancel, relief = "raised")
        self.buttonCancel.grid(row = 0, column = 2, sticky = 'e')
    
    def cancel(self):
        self.student_container.destroy()

class Faculty(Track):

    def __init__(self, master):
        super().__init__(master)
        self.faculty_container()

    def faculty_container(self):
        self.master.title("Faculty Program")
        tk.Message(self, text = "Faculty", font = 'arial 20 bold', justify = 'center', aspect = 800 ).pack(pady = (15, 0), side = 'top') 
        dialog_frame = tk.Frame(self, relief = 'raise', bg = 'lightgrey', height = 100, bd = 10)
        dialog_frame.pack(padx = 10, pady = 5, anchor = 'w')
        
        tk.Label(dialog_frame, text = "Academic Rank: ", bg = 'lightgrey', font = 'arial 13').grid(row = 0, column = 0, sticky = 'w')
        self.entry1 = tk.Entry(dialog_frame, fg = 'black',font = 'arial 13', width = 25, bd = 3, relief = "sunken")
        self.entry1.grid(row = 0, column = 1, sticky = 'w')
    
        tk.Label(dialog_frame, bg = 'lightgrey', text = "Academic research: " , font = 'arial 13').grid(row = 1, column = 0, sticky = 'w')
        self.entry2 = tk.Entry(dialog_frame, fg = 'black',font = 'arial 13', width = 25, bd = 3, relief = "sunken")
        self.entry2.grid(row = 1, column = 1, sticky = 'w')

        button_frame = tk.Frame(self)
        button_frame.pack(padx = 10, pady = 1, anchor = 'n')

        self.buttonSave = tk.Button(button_frame, text = 'Save',font = 'arial 13', activebackground = 'green', cursor = 'cross', command = self.save, relief = "raised")
        self.buttonSave.grid(row = 0, column = 1, sticky = 'w')
        self.buttonCancel = tk.Button(button_frame, text = 'Cancel',font = 'arial 13', activebackground = 'red', cursor = 'circle', command = self.cancel, relief = "raised")
        self.buttonCancel.grid(row = 0, column = 2, sticky = 'e')

    def cancel(self):
        self.faculty_container.destroy()

class Staff(Track):
    def __init__(self, master):
        super().__init__(master)
        self.staff_container()
    
    def staff_container(self):
        self.master.title("Staff Program")
        tk.Message(self, text = "Staff", font = 'arial 20 bold', justify = 'center', aspect = 800 ).pack(pady = (15, 0), side = 'top') 
        dialog_frame = tk.Frame(self, relief = 'raise', bg = 'lightgrey', height = 100, bd = 10)
        dialog_frame.pack(padx = 10, pady = 5, anchor = 'w')
        
        tk.Label(dialog_frame, text = "Position: ", bg = 'lightgrey', font = 'arial 13').grid(row = 0, column = 0, sticky = 'w')
        self.entry1 = tk.Entry(dialog_frame, fg = 'black',font = 'arial 13', width = 25, bd = 3, relief = "sunken")
        self.entry1.grid(row = 0, column = 1, sticky = 'w')
    
        tk.Label(dialog_frame, bg = 'lightgrey', text = "office: " , font = 'arial 13').grid(row = 1, column = 0, sticky = 'w')
        self.entry2 = tk.Entry(dialog_frame, fg = 'black',font = 'arial 13', width = 25, bd = 3, relief = "sunken")
        self.entry2.grid(row = 1, column = 1, sticky = 'w')

        button_frame = tk.Frame(self)
        button_frame.pack(padx = 10, pady = 1, anchor = 'n')

        self.buttonSave = tk.Button(button_frame, text = 'Save',font = 'arial 13', activebackground = 'green', cursor = 'cross', command = self.save, relief = "raised")
        self.buttonSave.grid(row = 0, column = 1, sticky = 'w')
        self.buttonCancel = tk.Button(button_frame, text = 'Cancel',font = 'arial 13', activebackground = 'red', cursor = 'circle', command = self.cancel, relief = "raised")
        self.buttonCancel.grid(row = 0, column = 2, sticky = 'e')

    def cancel(self):
        self.staff_container.destroy()


print(help(Student))
 

if __name__ == '__main__':
    root = tk.Tk()
    app = Track(root)
    app.mainloop()