docstr: Check if the n_out is valid.
docstr_tok: ["Check","if","the","n_out","is","valid","."]
code: def _check_n_out(n_out: int) -> None:
      """Check if the n_out is valid."""
      assert isinstance(n_out, (int, np.integer))
      assert n_out > 0
  
imports: from __future__ import annotations
  import re
  from abc import ABC, abstractmethod
  from typing import List, Optional, Tuple
  import numpy
label_desc: Use image node_id 2 for calling the AbstractAggregator obj's underlying member method code with example usage: obj._check_n_out(n_out) without return types