Python TextBox entry Hint(Invisible text)

Question

I am trying to create a text box with a hint inside of it. Like in the picture below. I tried using Hint and else but it would not work.

master = Tk.Tk() # Open up GUI connection
master.title('Program Application')
Label(text='Correct Range for Gradient').pack(side=TOP,padx=10,pady=10)
entryX1 = Entry(master, width=10).pack(side=LEFT,padx=10,pady=10)
entryX2 = Entry(master, width=10).pack(side=LEFT,padx=10,pady=10)
entryY1 = Entry(master,width=10).pack(side=RIGHT,padx=10,pady=10)
entryY2 = Entry(master,width=10).pack(side=RIGHT,padx=10,pady=10)
master.mainloop() 

How can i make it to have my text box to have a hint(invisible text) inside