diff --git a/climetlab/readers/bzip.py b/climetlab/readers/bzip.py
index 9d68013f..d6d07d6a 100644
--- a/climetlab/readers/bzip.py
+++ b/climetlab/readers/bzip.py
@@ -8,7 +8,6 @@
 #
 
 import bz2
-import os
 
 from . import Reader
 from . import reader as find_reader
@@ -33,7 +32,7 @@ def uncompress(target, _):
         )
 
     def mutate(self):
-        print('mutare', self.source, self.unzipped)
+        print("mutare", self.source, self.unzipped)
         return find_reader(self.source, self.unzipped)
 
 
diff --git a/climetlab/readers/grib/pytorch.py b/climetlab/readers/grib/pytorch.py
index 37a59f48..de971925 100644
--- a/climetlab/readers/grib/pytorch.py
+++ b/climetlab/readers/grib/pytorch.py
@@ -11,8 +11,6 @@
 
 import numpy as np
 
-# from climetlab.ml.torch import to_pytorch_dataloader
-
 from .tensorflow import default_merger, to_funcs
 
 LOG = logging.getLogger(__name__)
@@ -63,6 +61,8 @@ def __getitem__(self, i):  # -> Tuple[np.ndarray, ...]:
 
 class PytorchMixIn:
     def to_pytorch_dataloader(self, *args, dataloader_kwargs=None, **kwargs):
+        from climetlab.ml.torch import to_pytorch_dataloader
+
         if dataloader_kwargs is None:
             dataloader_kwargs = {}
         dataset = self.to_pytorch(*args, **kwargs)
diff --git a/climetlab/utils/patterns.py b/climetlab/utils/patterns.py
index 86903411..3727338f 100644
--- a/climetlab/utils/patterns.py
+++ b/climetlab/utils/patterns.py
@@ -17,6 +17,7 @@
 
 RE3 = re.compile(r"\(([^}]*)\)")
 
+
 class Any:
     def substitute(self, value, name):
         return value
@@ -115,11 +116,13 @@ def substitute(self, params):
             raise ValueError("Missing parameter '{}'".format(self.name))
         return self.kind.substitute(params[self.name], self.name)
 
+
 FUNCTIONS = dict(lower=lambda s: s.lower())
 
+
 class Function:
     def __init__(self, value):
-        functions = value.split('|')
+        functions = value.split("|")
         self.name = functions[0]
         self.variable = Variable(functions[0])
         self.functions = functions[1:]
@@ -131,7 +134,6 @@ def substitute(self, params):
         return value
 
 
-
 class Pattern:
     def __init__(self, pattern, ignore_missing_keys=False):
         self.ignore_missing_keys = ignore_missing_keys
@@ -142,7 +144,7 @@ def __init__(self, pattern, ignore_missing_keys=False):
             if i % 2 == 0:
                 self.pattern.append(Constant(p))
             else:
-                if '|' in p:
+                if "|" in p:
                     v = Function(p)
                 else:
                     v = Variable(p)
diff --git a/climetlab/version b/climetlab/version
index 19270385..c3f65805 100644
--- a/climetlab/version
+++ b/climetlab/version
@@ -1 +1 @@
-0.16.5
+0.16.6