diff --git a/tensorflow_data_validation/api/validation_api.py b/tensorflow_data_validation/api/validation_api.py
index 4d4df08a..d7855b6c 100644
--- a/tensorflow_data_validation/api/validation_api.py
+++ b/tensorflow_data_validation/api/validation_api.py
@@ -22,6 +22,7 @@
 import logging
 import apache_beam as beam
 import pyarrow as pa
+import pandas as pd
 import tensorflow as tf
 from tensorflow_data_validation import constants
 from tensorflow_data_validation import types
@@ -52,6 +53,17 @@
     anomalies_pb2.AnomalyInfo.NO_DATA_IN_SPAN,
 ])
 
+def preprocess_numerical_to_categorical_by_own_quantiles(
+    dataframe: pd.DataFrame,
+):
+  # TODO: refactor implementation from private project
+  return dataframe
+
+def preprocess_numerical_to_categorical_by_training_quantiles(
+    dataframe: pd.DataFrame,
+):
+  # TODO: refactor implementation from private project
+  return dataframe
 
 def infer_schema(
     statistics: statistics_pb2.DatasetFeatureStatisticsList,