code: def griewank(x: np.ndarray) -> float:
      """Multimodal function, often used in Bayesian optimization."""
      part1 = sphere(x)
      part2 = np.prod(np.cos(x / np.sqrt(1 + np.arange(len(x)))))
      return 1 + (float(part1) / 4000.0) - float(part2)
  
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 25 for calling a global function with example usage: griewank(x) and returns: unknown