Set a pixel

def point(self, x, y, color=None):
        """Set a pixel"""
        if x < 0 or y < 0 or x > self.width - 1 or y > self.height - 1:
            return
        if color is None:
            color = self.color
        o = self._offset(x, y)

        self.canvas[o:o + 3] = blend(self.canvas[o:o + 3], bytearray(color))