diff --git a/hub_module/modules/text/semantic_model/lda_news/document.py b/hub_module/modules/text/semantic_model/lda_news/document.py
index d9a5426f26652aadb368877e1ebb1ffb0bd821c7..b79acd0794f60fb0a401726aea0b8b51deda90a1 100644
--- a/hub_module/modules/text/semantic_model/lda_news/document.py
+++ b/hub_module/modules/text/semantic_model/lda_news/document.py
@@ -97,7 +97,7 @@ class LDADoc(object):
         topic_dist = []
         sum_ = np.sum(self._accum_topic_sum)
         if sum_ == 0:
-            return
+            return topic_dist
         for i in range(0, self._num_topics):
             if self._accum_topic_sum[i] == 0:
                 continue
diff --git a/hub_module/modules/text/semantic_model/lda_novel/document.py b/hub_module/modules/text/semantic_model/lda_novel/document.py
index d9a5426f26652aadb368877e1ebb1ffb0bd821c7..b79acd0794f60fb0a401726aea0b8b51deda90a1 100644
--- a/hub_module/modules/text/semantic_model/lda_novel/document.py
+++ b/hub_module/modules/text/semantic_model/lda_novel/document.py
@@ -97,7 +97,7 @@ class LDADoc(object):
         topic_dist = []
         sum_ = np.sum(self._accum_topic_sum)
         if sum_ == 0:
-            return
+            return topic_dist
         for i in range(0, self._num_topics):
             if self._accum_topic_sum[i] == 0:
                 continue
diff --git a/hub_module/modules/text/semantic_model/lda_webpage/document.py b/hub_module/modules/text/semantic_model/lda_webpage/document.py
index d9a5426f26652aadb368877e1ebb1ffb0bd821c7..b79acd0794f60fb0a401726aea0b8b51deda90a1 100644
--- a/hub_module/modules/text/semantic_model/lda_webpage/document.py
+++ b/hub_module/modules/text/semantic_model/lda_webpage/document.py
@@ -97,7 +97,7 @@ class LDADoc(object):
         topic_dist = []
         sum_ = np.sum(self._accum_topic_sum)
         if sum_ == 0:
-            return
+            return topic_dist
         for i in range(0, self._num_topics):
             if self._accum_topic_sum[i] == 0:
                 continue
diff --git a/hub_module/modules/text/semantic_model/slda_news/document.py b/hub_module/modules/text/semantic_model/slda_news/document.py
index d9a5426f26652aadb368877e1ebb1ffb0bd821c7..b79acd0794f60fb0a401726aea0b8b51deda90a1 100644
--- a/hub_module/modules/text/semantic_model/slda_news/document.py
+++ b/hub_module/modules/text/semantic_model/slda_news/document.py
@@ -97,7 +97,7 @@ class LDADoc(object):
         topic_dist = []
         sum_ = np.sum(self._accum_topic_sum)
         if sum_ == 0:
-            return
+            return topic_dist
         for i in range(0, self._num_topics):
             if self._accum_topic_sum[i] == 0:
                 continue
diff --git a/hub_module/modules/text/semantic_model/slda_novel/document.py b/hub_module/modules/text/semantic_model/slda_novel/document.py
index d9a5426f26652aadb368877e1ebb1ffb0bd821c7..b79acd0794f60fb0a401726aea0b8b51deda90a1 100644
--- a/hub_module/modules/text/semantic_model/slda_novel/document.py
+++ b/hub_module/modules/text/semantic_model/slda_novel/document.py
@@ -97,7 +97,7 @@ class LDADoc(object):
         topic_dist = []
         sum_ = np.sum(self._accum_topic_sum)
         if sum_ == 0:
-            return
+            return topic_dist
         for i in range(0, self._num_topics):
             if self._accum_topic_sum[i] == 0:
                 continue
diff --git a/hub_module/modules/text/semantic_model/slda_webpage/document.py b/hub_module/modules/text/semantic_model/slda_webpage/document.py
index d9a5426f26652aadb368877e1ebb1ffb0bd821c7..b79acd0794f60fb0a401726aea0b8b51deda90a1 100644
--- a/hub_module/modules/text/semantic_model/slda_webpage/document.py
+++ b/hub_module/modules/text/semantic_model/slda_webpage/document.py
@@ -97,7 +97,7 @@ class LDADoc(object):
         topic_dist = []
         sum_ = np.sum(self._accum_topic_sum)
         if sum_ == 0:
-            return
+            return topic_dist
         for i in range(0, self._num_topics):
             if self._accum_topic_sum[i] == 0:
                 continue
diff --git a/hub_module/modules/text/semantic_model/slda_weibo/document.py b/hub_module/modules/text/semantic_model/slda_weibo/document.py
index d9a5426f26652aadb368877e1ebb1ffb0bd821c7..b79acd0794f60fb0a401726aea0b8b51deda90a1 100644
--- a/hub_module/modules/text/semantic_model/slda_weibo/document.py
+++ b/hub_module/modules/text/semantic_model/slda_weibo/document.py
@@ -97,7 +97,7 @@ class LDADoc(object):
         topic_dist = []
         sum_ = np.sum(self._accum_topic_sum)
         if sum_ == 0:
-            return
+            return topic_dist
         for i in range(0, self._num_topics):
             if self._accum_topic_sum[i] == 0:
                 continue