code: def missing_io_signature_helper() -> str:
      """Helper function to print the error message when the input/output signature is missing
  
      Args:
          io_type (str, optional): "input" or "output". Defaults to "input".
  
      Returns:
          str: Error message
      """
      signature_template = """
      You can define the io signature using the decorator as follows:
      @forward(
          input_signatures=[
              PandasDataframe(
                  columns=[<List of cols>],
                  column_types=[<List of col types>],
                  column_shapes=[<List of col shapes>],
              )
          ],
          output_signatures=[
              PandasDataframe(
                  columns=[<List of cols>],
                  column_types=[<List of col types>],
                  column_shapes=[<List of col shapes>],
              )
          ],
      )
      More information on the how to create the forward decorator can be found here:
      https://evadb.readthedocs.io/en/stable/source/reference/ai/custom-ai-function.html#part-1-writing-a-custom-function
      """
  
      return signature_template
  
imports: from typing import List, Type
  from evadb.catalog.models.function_io_catalog import FunctionIOCatalogEntry
  from evadb.functions.abstract.abstract_function import AbstractFunction
label_desc: Use image node_id 1 for calling a global function with example usage: missing_io_signature_helper() and returns: signature_template