class_docstr: A dictionary with numeric keys that looks up the closest key.
code: def __setitem__(self, key: Number, val: Any) -> None:
      if not isinstance(key, Number):
          raise ValueError(
              "ClosestLookupDict only allows numerical keys."
          )
      super().__setitem__(key, val)
      ipos = np.searchsorted(self._keys, key)
      self._keys.insert(ipos, key)
  
imports: from __future__ import annotations
  from collections import defaultdict
  from math import isnan
  from numbers import Number
  from typing import Any, Callable, Dict, List, Optional, Tuple, TYPE_CHECKING, Union
  import numpy
  from ax.core.observation import Observation, ObservationData, ObservationFeatures
  from ax.core.optimization_config import OptimizationConfig
  from ax.core.parameter import Parameter
  from ax.core.parameter_constraint import ParameterConstraint
  from ax.core.search_space import RobustSearchSpace, SearchSpace
  from ax.modelbridge.transforms.derelativize import Derelativize
  from scipy.stats import norm
label_desc: Use image node_id 2 for calling the ClosestLookupDict obj's underlying member method code with example usage: obj.__setitem__(key, val) without return types