def pixel(self, ix, iy):
        """Return color for a pixel.

        Does translation from image coordinates (ix,iy) into
        the complex plane coordinate z = x+yi, and then calls
        self.mpixel(z) to find the color at point z.
        """
        x = (ix - self.xoffset + 0.5) / self.scale
        y = (iy - self.yoffset + 0.5) / self.scale
        z = complex(x, y)
        self.set_c(z)
        return self.mpixel(z)
Return color for a pixel.

        Does translation from image coordinates (ix,iy) into
        the complex plane coordinate z = x+yi, and then calls
        self.mpixel(z) to find the color at point z.