on_chain_start

on_chain_start(
  self,
  serialized: dict[str, Any],
  inputs: dict[str, Any],
  *,
  run_id: UUID,
  parent_run_id: UUID | None = None,
  tags: list[str] | None = None,
  metadata: dict[str, Any] | None = None,
  **kwargs: Any = {}
) -> Any