diff --git a/aiida_nanotech_empa/workflows/cp2k/__init__.py b/aiida_nanotech_empa/workflows/cp2k/__init__.py
index f3d435d..e77edc6 100644
--- a/aiida_nanotech_empa/workflows/cp2k/__init__.py
+++ b/aiida_nanotech_empa/workflows/cp2k/__init__.py
@@ -10,8 +10,8 @@
 from .orbitals_workchain import Cp2kOrbitalsWorkChain
 from .pdos_workchain import Cp2kPdosWorkChain
 from .phonons_workchain import Cp2kPhononsWorkChain
-from .replica_workchain import Cp2kReplicaWorkChain
 from .reftraj_md_workchain import Cp2kMdReftrajWorkChain
+from .replica_workchain import Cp2kReplicaWorkChain
 from .stm_workchain import Cp2kStmWorkChain
 
 __all__ = (
diff --git a/examples/workflows/example_cp2k_md_reftraj.py b/examples/workflows/example_cp2k_md_reftraj.py
index 0f6dfa0..4db6fc3 100644
--- a/examples/workflows/example_cp2k_md_reftraj.py
+++ b/examples/workflows/example_cp2k_md_reftraj.py
@@ -1,10 +1,9 @@
-import pathlib
 import os
 import random
-import numpy as np
 
 import ase.io
 import click
+import numpy as np
 from aiida import engine, orm, plugins
 from ase import Atoms
 
@@ -14,7 +13,6 @@
 
 
 def _example_cp2k_reftraj(cp2k_code):
-
     thisdir = os.path.dirname(os.path.realpath(__file__))
 
     # Structure.
@@ -79,7 +77,7 @@ def _example_cp2k_reftraj(cp2k_code):
 
 
 def example_cp2k_reftraj(cp2k_code):
-    pk1 = _example_cp2k_reftraj(cp2k_code)
+    _example_cp2k_reftraj(cp2k_code)
     # _example_cp2k_replicachain(cp2k_code, pk1)