Create dialog body. Return widget that should have initial
        focus.

        Inherited from tkinter.simpledialog.Dialog

def body(self, master):
        """Create dialog body. Return widget that should have initial
        focus.

        Inherited from tkinter.simpledialog.Dialog
        """
        self.frame = ttk.Frame(master, padding=(5, 5, 10, 10))

        self.lbl_message = ttk.Label(
            self.frame,
            text='Select User Type: ',
        )
        self.rb_student = ttk.Radiobutton(
            self.frame,
            text='Student',
            variable=self.rb_choice,
            value='student',
        )
        self.rb_tutor = ttk.Radiobutton(
            self.frame,
            text='Tutor',
            variable=self.rb_choice,
            value='tutor',
        )
        self.btn_ok = ttk.Button(
            self.frame,
            text='OK',
            command=self.ok,
        )
        self.btn_cancel = ttk.Button(
            self.frame,
            text='Cancel',
            command=self.cancel,
        )
        # assemble grid
        self.frame.grid(column=0, row=0, sticky=(N, S, E, W))
        self.lbl_message.grid(column=0, row=0, columnspan=2, sticky=(W, E))
        self.rb_student.grid(column=0, row=1, columnspan=2, sticky=W)
        self.rb_tutor.grid(column=0, row=2, columnspan=2, sticky=W)
        self.btn_ok.grid(column=0, row=3)
        self.btn_cancel.grid(column=1, row=3)

        # key bindings
        self.bind('<Return>', self.ok)
        self.bind('<KP_Enter>', self.ok)
        self.bind('<Escape>', self.cancel)

        self.rb_tutor.invoke()

        return self.btn_ok