Mine

import Blender
import Blender.Node as bN
import math
from Blender import Noise

class CloudNode(bN.Node):
    input_def = {'turbulence':(bN.VALUE, 0.25, 1.0, 1.0, 1.0,  0.0, 10.0)}
    output_def = {'colour':(bN.VALUE, 0.25, 1.0, 1.0, 1.0,  0.0, 10.0)}
    
    def __call__(self, node):
        return  Noise.turbulence(node.tex_coord, 2, 0, 1, 0.5, 2.0)

bN.Node.register(CloudNode)