code: def bucherastrigin(x: np.ndarray) -> float:
      """Classical multimodal function. No box-constraint penalization here."""
      s = np.asarray(
          [
              x[i]
              * (10 if x[i] > 0.0 and i % 2 else 1)
              * (10 ** ((i - 1) / (2 * (len(x) - 1))))
              for i in range(len(x))
          ]
      )
      cosi = float(np.sum(np.cos(2 * np.pi * s)))
      return float(10 * (len(x) - cosi) + sphere(s))
  
imports: from math import exp, sqrt, tanh
  import numpy
  import nevergrad.common.typing
  from nevergrad.common.decorators import Registry
label_desc: Use image node_id 18 for calling a global function with example usage: bucherastrigin(x) and returns: float