r = 0.9 (slider from 0 to 5, step 0.1)
R = 2.5 (slider from 0 to 5, step 0.1)
a = Surface(((R + (r * cos(u))) * cos(v)), ((R + (r * cos(u))) * sin(v)), (r * sin(u)), u, 0, 6.283185307179586, v, 0, 6.283185307179586)