diff --git a/src/rbm/stack_factory.py b/src/rbm/stack_factory.py
index ad09521..c926609 100644
--- a/src/rbm/stack_factory.py
+++ b/src/rbm/stack_factory.py
@@ -1,19 +1,16 @@
 import json
 from collections.abc import Callable
-from stack import StackType
+from stack import Stack, StackType
 from layer import Layer
 from params import RbmParams
+
 from stack_deep import StackDeep
 from stack_rnn import StackRnn
 
 
 class StackFactory:
-	def __init__(self):
-		pass
-
-
 	@classmethod
-	def from_dict(cls, project: dict, layer_constructor: Callable = None):
+	def from_dict(cls, project: dict, layer_constructor: Callable = None) -> Stack:
 		name = project["stack"]["name"]
 		layers = project["stack"]["layers"]
 
@@ -59,7 +56,7 @@ class StackFactory:
 		return obj
 
 	@classmethod
-	def from_file(cls, filename: str, layer_constructor: Callable = None):
+	def from_file(cls, filename: str, layer_constructor: Callable = None) -> Stack:
 		obj = None
 		with open(filename, "r") as fp:
 			prj = json.load(fp)