def mandelbrot(xint, yint, size, maxreps):
width, height = size
img = ImagePPM.new(size)
for i in range(width):
for j in range(height):
a = lerp(i / width, xint[0], xint[1])
b = lerp(1 - j / height, yint[0], yint[1])
c = complex(a, b)
img.putpixel((i, j), testpoint(c, maxreps))
return img