new_contents: # Create the data.
  from numpy import pi, sin, cos, mgrid
  [u,v] = mgrid[-5:5:0.01,0:2*pi+0.1:0.1]
  a=2
  
  x = u*cos(v)
  y = u*sin(v)
  z = a*v
  K=-a**2/(u**2 +a**2)**2
  
  from mayavi import mlab
  s = mlab.mesh(x, y, z,scalars=K)
  mlab.show()
  
subject: Create helix.py