class_docstr: Raised when a required sample with a particular label is missing.
class_docstr_tok: ["Raised","when","a","required","sample","with","a","particular","label","is","missing","."]
code: def __init__(
      self, label_or_msg: str, keys: list[str] | None = None
  ) -> None:
      if keys is None:
          super().__init__(label_or_msg)
      else:
          super().__init__(
              f"Label {label_or_msg} is missing from sample. Existing keys are: {keys}"
          )
  
file_path: nni/nni/mutable/exception.py
imports: from __future__ import annotations
  from typing import overload
label_desc: Use image node_id 3 to create a new SampleMissingError object from inherited base classes: SampleValidationError with example: obj = SampleMissingError(label_or_msg, keys)