code: def test_ptb_no_overfitting() -> None:
      func = functionlib.PBT(("sphere", "cigar"), (3, 7), 12)
      func = func.copy()
      # We do a gradient descent.
      value = [func(-15.0 * np.ones(2)) for _ in range(1500)]
      # We check that the values are becoming better and better.
      assert value[-1] < value[len(value) // 2]  # type: ignore
      assert value[0] > value[len(value) // 2]
  
imports: import typing
  import numpy
  import pytest
  from nevergrad.common import testing
  from nevergrad.parametrization import parameter
  from .None import functionlib
label_desc: Use image node_id 3 for calling a global function with example usage: test_ptb_no_overfitting() without return types