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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _update_preview(self):
 """Update color preview."""

        color = self.hexa.get()
        if self.alpha_channel:
            prev = overlay(self._transparent_bg, hexa_to_rgb(color))
            self._im_color = ImageTk.PhotoImage(prev, master=self)
            self.color_preview.configure(image=self._im_color)
        else:
            self.color_preview.configure(background=color)