diff --git a/embedding.py b/embedding.py
index 63dee8b..e6f0390 100755
--- a/embedding.py
+++ b/embedding.py
@@ -111,7 +111,7 @@ def add_keyword_corpus(self, keyword, sentences):
 					self.sentences = list(set(self.sentences))
 
 			else:
-				
+
 				self.kc[keyword] = set(sentences)
 				self.sentences.extend(sentences)
 				self.sentences = list(set(self.sentences))
diff --git a/preprocessing.py b/preprocessing.py
index af31f1d..2d6aa47 100644
--- a/preprocessing.py
+++ b/preprocessing.py
@@ -114,7 +114,7 @@ def __init__(self, keywords, case_sensitive=False, worker=3):
 	# 		self.kc[keyword] = set(sentences)
 
 
-	def _create(self, keywords, sentences, chunksize=256):
+	def _create(self, keywords, sentences, chunksize=5000):
 
 		sentences_chunk = []
 		partition_size = chunksize // self.corpus_worker
diff --git a/sec2vec_decorator.py b/sec2vec_decorator.py
new file mode 100644
index 0000000..dca5edf
--- /dev/null
+++ b/sec2vec_decorator.py
@@ -0,0 +1,40 @@
+from collections import Iterator
+
+def assert_sentences(f):
+	'''
+	Normalize the input sentences' data structure
+	'''
+
+	def inner(self, k=None, sentences=None, corpus_file=None, *args): 
+	# def inner(self, k=None, sentences=None, *args): 
+		'''
+		:param k: keywords or keyword
+		:type k: str or list of str
+		:param sentences: input sentences for training.
+		:type sentences: str, list of str or list of listed tokens
+		:param corpus_file: path for corpus
+		:type corpus_file: str
+		'''
+
+		if isinstance(sentences, str):
+			return f(self, k, [sentences], corpus_file, *args)
+
+		elif isinstance(sentences, Iterator):
+			return f(self, k, sentences, corpus_file, *args)
+
+		elif isinstance(sentences, list):
+
+			_sentences = []
+
+			for s in sentences:
+
+				if isinstance(s, str):
+					_sentences.append(s)
+				else:
+					_sentences.append(' '.join(s))
+
+			return f(self, k, _sentences, corpus_file, *args)
+
+		return f(self, k, sentences, corpus_file, *args)
+
+	return inner
\ No newline at end of file