Using a class to create instances of Tkinter Toplevel() windows

[nortski]

I'm a newbie at python and coding in general. I am messing around with Tkinter, trying to understand it. Before I go any further can someone tell me if it's ok practice to create a class to initialise Toplevel() windows?

This is my code, please pull it to pieces:

from tkinter import *

class TopLevelWindow():
    def __init__(self, master, width, height):
        self.master = master
        self.master.geometry("%sx%s+100+100" % (width, height))
        self.master.title("Toplevel Window")


root = Tk()
top1 = Toplevel()
top2 = Toplevel()
TopLevelWindow(top1, "300", "300")
TopLevelWindow(top2, "500", "250")

root.mainloop()

This code works but I really don't know what is happening, I just throw a few keywords together until it worked.
Can someone explain what is happening here where I pas in master and then define self.master as master. Is it even ALLOWED to be a master?

def __init__(self, master, width, height):
    self.master = master