code: def op_reference(operator, docstring, order=None):
      """Add a reference from operator to this notebook with specified docstring.
  
      Parameters
      ----------
      operator : str
          Name of operator without nvidia.dali prefix, for example fn.resize or fn.gaussian_blur
      docstring : str
          Text that would appear in the see also block for given link.
      order : int, optional
          The order in which this entry should appear - lower values appear on top
      """
      return OpReference(operator, docstring, order)
  
file_path: DALI/docs/doc_index.py
imports: from pathlib import Path
label_desc: Use image node_id 4 for calling a global function with example usage: op_reference(operator, docstring, order) and returns: OpReference