docstr: Get the number of outputs the step produces.
code: def n_outputs(self):
      """Get the number of outputs the step produces."""
      return self._n_outputs
  
imports: import inspect
  import warnings
  from typing import Any, Callable, Dict, List, Optional, Union, TYPE_CHECKING
  from baikal._core.data_placeholder import DataPlaceholder, is_data_placeholder_list
  from baikal._core.utils import listify, make_name, make_repr
label_desc: Use image node_id 9 for calling the _StepBase obj's underlying member method code with example usage: obj.n_outputs() and returns: self