class_docstr: An `Instance` represents one data point that we're evaluating on (e.g., one
  question in a QA task).
  Note: `eq=False` means that we hash by the identity.
docstr: Return the first correct reference.
docstr_tok: ["Return","the","first","correct","reference","."]
code: def first_correct_reference(self) -> Optional[Reference]:
      """Return the first correct reference."""
      for reference in self.references:
          if reference.is_correct:
              return reference
      return None
  
imports: from abc import ABC, abstractmethod
  from dataclasses import dataclass, field, replace
  from typing import List, Optional, Tuple
  import re
  import inspect
  from helm.common.object_spec import ObjectSpec, create_object
  from helm.common.general import format_text, format_split, format_tags, indent_lines
  from helm.benchmark.augmentations.perturbation_description import PerturbationDescription
label_desc: Use image node_id 1 for calling the Instance obj's underlying member method code with example usage: obj.first_correct_reference() and returns: None, reference