code: def df_without_columns():
      return pd.DataFrame({0: [1, 2, 3], 1: [4, 5, 6], 2: [7, 8, 9]})
  
imports: import json
  import math
  from unittest import mock
  import numpy
  import pandas
  import pytest
  import sklearn.neighbors
  from scipy.sparse import csc_matrix, csr_matrix
  from sklearn import datasets
  from sklearn.base import BaseEstimator, ClassifierMixin
  import mlflow
  from mlflow.models import Model
  from mlflow.models.signature import ModelSignature, infer_signature
  from mlflow.models.utils import _Example, _read_sparse_matrix_from_json, _read_tensor_input_from_json
  from mlflow.types import DataType
  from mlflow.types.schema import ColSpec, Schema, TensorSpec
  from mlflow.types.utils import TensorsNotSupportedException
  from mlflow.utils.file_utils import TempDir
  from mlflow.utils.proto_json_utils import dataframe_from_raw_json
  from tests.helper_functions import AnyStringWith
label_desc: Use image node_id 2 for calling a global function with example usage: df_without_columns() and returns: pd