diff --git a/.github/CONTRIBUTING.md b/.github/CONTRIBUTING.md
index 6640f332..109c5b7c 100644
--- a/.github/CONTRIBUTING.md
+++ b/.github/CONTRIBUTING.md
@@ -8,7 +8,7 @@ For example: One benefit of the validation_step is that the user doesn't have to
 
 ## Lightning Design Principles   
 We encourage all sorts of contributions you're interested in adding! When coding for lightning, please follow these principles.    
-#### No PyTorch interference   
+#### No PyTorch Interference   
 We don't want to add any abstractions on top of pure PyTorch. This gives researchers all the control they need without having to learn yet another framework.    
 
 #### Simple Internal Code    
@@ -30,12 +30,12 @@ You shouldn't be afraid to upgrade Lightning :)
 #### Gain User Trust    
 As a researcher you can't have any part of your code going wrong. So, make thorough tests that ensure an implementation of a new trick or subbtle change is correct.    
 
-## Contribution types    
+## Contribution Types    
 Currently looking for help implementing new features or adding bug fixes. 
 
 A lot of good work has already been done in project mechanics (requirements.txt, setup.py, pep8, badges, ci, etc...) we're in a good state there thanks to all the early contributors (even pre-beta release)!   
 
-## Bug fixes:  
+## Bug Fixes:  
 1. Submit a github issue.   
 2. Fix it.  
 3. Submit a PR! 
@@ -44,3 +44,7 @@ A lot of good work has already been done in project mechanics (requirements.txt,
 1. Submit a github issue.   
 2. We'll agree on the feature scope.     
 3. Submit a PR! (with updated docs and tests 🙃).   
+
+## Coding Styleguide
+1. Test the code with flake8.
+2. Use f-strings.
diff --git a/tests/test_cpu_models.py b/tests/test_cpu_models.py
index 62f30404..1b7a2573 100644
--- a/tests/test_cpu_models.py
+++ b/tests/test_cpu_models.py
@@ -299,6 +299,8 @@ def test_tbptt_cpu_model():
     """
     testing_utils.reset_seed()
 
+    save_dir = testing_utils.init_save_dir()
+
     truncated_bptt_steps = 2
     sequence_size = 30
     batch_size = 30
@@ -366,6 +368,8 @@ def test_tbptt_cpu_model():
 
     assert result == 1, 'training failed to complete'
 
+    testing_utils.clear_save_dir()
+
 
 def test_single_gpu_model():
     """