code: def pad_empty_string(
      split_lists: Union[list, np.ndarray],
      padding_requirement: Union[list, int],
  ) -> list:
      if isinstance(split_lists, list):
          return split_lists + ["" for _ in range(padding_requirement)]
      if isinstance(split_lists, np.ndarray):
          return list(
              map(pad_empty_string, split_lists, padding_requirement)
          )
      raise TypeError(f"Invalid array type '{type(split_lists)}'")
  
file_path: onnx/onnx/reference/ops/op_string_split.py
imports: from typing import Union
  import numpy
  from onnx.reference.op_run import OpRun
label_desc: Use image node_id 1 for calling a global function with example usage: pad_empty_string(split_lists, padding_requirement) and returns: unknown, list