How to use the ttkwidgets.color.functions.rgb_to_hexa function in ttkwidgets

def test_rgb_to_hexa(self):
        self.assertEqual(tkf.rgb_to_hexa(255, 255, 255), "#FFFFFF")
        self.assertEqual(tkf.rgb_to_hexa(255, 255, 255, 255), "#FFFFFFFF")
        self.assertRaises(ValueError, tkf.rgb_to_hexa, 255, 255)

def test_rgb_to_hexa(self):
        self.assertEqual(tkf.rgb_to_hexa(255, 255, 255), "#FFFFFF")
        self.assertEqual(tkf.rgb_to_hexa(255, 255, 255, 255), "#FFFFFFFF")
        self.assertRaises(ValueError, tkf.rgb_to_hexa, 255, 255)

def get(self):
        """
        Get selected color.

        :return: color under cursor as a (RGB, HSV, HEX) tuple
        """
        x = self.coords('cross_v')[0]
        y = self.coords('cross_h')[1]
        xp = min(x, self.bg.width() - 1)
        yp = min(y, self.bg.height() - 1)
        try:
            r, g, b = self.bg.get(round2(xp), round2(yp))
        except ValueError:
            r, g, b = self.bg.get(round2(xp), round2(yp)).split()
            r, g, b = int(r), int(g), int(b)
        hexa = rgb_to_hexa(r, g, b)
        h = self.get_hue()
        s = round2((1 - float(y) / self.winfo_height()) * 100)
        v = round2(100 * float(x) / self.winfo_width())
        return (r, g, b), (h, s, v), hexa

def _palette_cmd(self, event):
        """Respond to user click on a palette item."""
        label = event.widget
        label.master.focus_set()
        label.master.configure(relief="sunken")
        r, g, b = self.winfo_rgb(label.cget("background"))
        r = round2(r * 255 / 65535)
        g = round2(g * 255 / 65535)
        b = round2(b * 255 / 65535)
        args = (r, g, b)
        if self.alpha_channel:
            a = self.alpha.get()
#            a = self.get_color_value(self.alpha)
            args += (a,)
            self.alphabar.set_color(args)
        color = rgb_to_hexa(*args)
        h, s, v = rgb_to_hsv(r, g, b)
        self.red.set(r)
        self.green.set(g)
        self.blue.set(b)
        self.hue.set(h)
        self.saturation.set(s)
        self.value.set(v)
        self.hexa.delete(0, "end")
        self.hexa.insert(0, color.upper())
        self.bar.set(h)
        self.square.set_hsv((h, s, v))
        self._update_preview()

"""Create the gradient."""
        r, g, b = hue2col(self._hue)
        width = self.winfo_width()
        height = self.winfo_height()
        h = float(height - 1)
        w = float(width - 1)
        if height:
            c = [(r + i / h * (255 - r), g + i / h * (255 - g), b + i / h * (255 - b)) for i in range(height)]
            data = []
            for i in range(height):
                line = []
                for j in range(width):
                    rij = round2(j / w * c[i][0])
                    gij = round2(j / w * c[i][1])
                    bij = round2(j / w * c[i][2])
                    color = rgb_to_hexa(rij, gij, bij)
                    line.append(color)
                data.append("{" + " ".join(line) + "}")
            self.bg.put(" ".join(data))

col = self.winfo_rgb(color)
                self._old_color = tuple(round2(c * 255 / 65535) for c in col)
                args = self._old_color
                if alpha:
                    self._old_alpha = 255
                    args = self._old_color + (255,)
                old_color = rgb_to_hexa(*args)
        else:
            self._old_color = color[:3]
            if alpha:
                if len(color) < 4:
                    color += (255,)
                    self._old_alpha = 255
                else:
                    self._old_alpha = color[3]
            old_color = rgb_to_hexa(*color)

        # --- GradientBar
        hue = col2hue(*self._old_color)
        bar = ttk.Frame(self, borderwidth=2, relief='groove')
        self.bar = GradientBar(bar, hue=hue, width=200, highlightthickness=0)
        self.bar.pack()

        # --- ColorSquare
        square = ttk.Frame(self, borderwidth=2, relief='groove')
        self.square = ColorSquare(square, hue=hue, width=200, height=200,
                                  color=rgb_to_hsv(*self._old_color),
                                  highlightthickness=0)
        self.square.pack()

        frame = ttk.Frame(self)
        frame.columnconfigure(1, weight=1)

def _update_color_rgb(self, event=None):
        """Update display after a change in the RGB spinboxes."""
        if event is None or event.widget.old_value != event.widget.get():
            r = self.red.get()
            g = self.green.get()
            b = self.blue.get()
            h, s, v = rgb_to_hsv(r, g, b)
            self.hue.set(h)
            self.saturation.set(s)
            self.value.set(v)
            args = (r, g, b)
            if self.alpha_channel:
                args += (self.alpha.get(),)
                self.alphabar.set_color(args)
            hexa = rgb_to_hexa(*args)
            self.hexa.delete(0, "end")
            self.hexa.insert(0, hexa)
            self.square.set_hsv((h, s, v))
            self.bar.set(h)
            self._update_preview()

def _update_color_hsv(self, event=None):
        """Update display after a change in the HSV spinboxes."""
        if event is None or event.widget.old_value != event.widget.get():
            h = self.hue.get()
            s = self.saturation.get()
            v = self.value.get()
            sel_color = hsv_to_rgb(h, s, v)
            self.red.set(sel_color[0])
            self.green.set(sel_color[1])
            self.blue.set(sel_color[2])
            if self.alpha_channel:
                sel_color += (self.alpha.get(),)
                self.alphabar.set_color(sel_color)
            hexa = rgb_to_hexa(*sel_color)
            self.hexa.delete(0, "end")
            self.hexa.insert(0, hexa)
            self.square.set_hsv((h, s, v))
            self.bar.set(h)
            self._update_preview()