code: def vdc(
      self, n: int, permut: tp.List[int]
  ) -> float:  # TODO speed up?
      base = len(permut)  # should be a prime number
      vdc, denom = 0.0, 1
      n += 1
      while n:
          denom *= base
          n, remainder = divmod(n, base)
          remainder = permut[remainder]
          vdc += float(remainder) / float(denom)
      return vdc
  
imports: import numpy
  from numpy.random import RandomState
  import nevergrad.common.typing
  from nevergrad.common.decorators import Registry
label_desc: Use image node_id 2 for calling the HaltonSampler obj's underlying member method code with example usage: obj.vdc(n, permut) and returns: vdc