Making a second window with Tkinter

[greenflame]

I have a script that will make a window that shows the text I want
using Tkinter. What I need to do is to make another window popup above
the current window showing other text. I tryed:

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from Tkinter imprt *

root = Tk()

L = Label(root, text="Blah")
L.grid(row=0, column=0)

# Other labels are also here but their inclusion is not so relavent.

root.mainloop()

sub = Tk()

subL = Label(root, text="Blah")
subL.grid(row=0, column=0)

sub.mainloop()
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However, when I ran the script it only showed the second window after I
closed the first one. After looking at the code I guess I can see why.
The problem is that I do not know how to fix the issue. Thank you for
you help.