code: def __init__(self, ref):
      super().__init__(f"'{ref}' is not a valid experiment refname.")
      self.ref = ref
  
imports: from typing import TYPE_CHECKING, Collection, Iterable, Optional
  from dvc.exceptions import DvcException, InvalidArgumentError
label_desc: Use image node_id 1 to create a new InvalidExpRefError object from inherited base classes: DvcException with example: obj = InvalidExpRefError(ref)