docstr: Value at global minimum(s).
code: def fmin(self) -> float:
      """Value at global minimum(s)."""
      return self._fmin
  
imports: from abc import ABC, abstractmethod
  from typing import Any, Callable, List, Optional, Tuple, Union
  import numpy
  import torch
  from ax.utils.common.docutils import copy_doc
  from ax.utils.common.typeutils import checked_cast, not_none
  from botorch.test_functions import synthetic
label_desc: Use image node_id 8 for calling the SyntheticFunction obj's underlying member method code with example usage: obj.fmin() and returns: self