def _update(self, frame_no):
        # Draw the new image to the required block.
        c = complex(self._c[0], self._c[1])
        sx = self._centre[0] - (self._size[0] / 2.0)
        sy = self._centre[1] - (self._size[1] / 2.0)
        for y in range(self._height):
            for x in range(self._width):
                z = complex(sx + self._size[0] * (x / self._width),
                            sy + self._size[1] * (y / self._height))
                n = len(self._256_palette)
                while abs(z) < 10 and n >= 1:
                    z = z ** 2 + c
                    n -= 1
                colour = \
                    self._256_palette[
                        1 - n] if self._screen.colours >= 256 else 7
                self._screen.print_at(self._greyscale[n - 1], x, y, colour)

        # Zoom
        self._size = [i * self._scale for i in self._size]
        area = self._size[0] * self._size[1]
        if area <= 4.0 or area >= 16:
            self._scale = 1.0 / self._scale

        # Rotate
        self._c = [self._c[0] * cos(pi / 180) - self._c[1] * sin(pi / 180),
                   self._c[0] * sin(pi / 180) + self._c[1] * cos(pi / 180)]
dataset/ETHPy150Open peterbrittain/asciimatics/asciimatics/effects.py/Julia._update/swapped operands of `-`