diff --git a/nbformat/reader.py b/nbformat/reader.py
index 465dac4a..71c32801 100644
--- a/nbformat/reader.py
+++ b/nbformat/reader.py
@@ -6,20 +6,24 @@
 import json
 from .validator import ValidationError
 
+
 class NotJSONError(ValueError):
     pass
 
+
 def parse_json(s, **kwargs):
     """Parse a JSON string into a dict."""
     try:
         nb_dict = json.loads(s, **kwargs)
     except ValueError as e:
         # Limit the error message to 80 characters.  Display whatever JSON will fit.
-        raise NotJSONError(("Notebook does not appear to be JSON: %r" % s)[:77] + "...") from e
+        raise NotJSONError(("Notebook does not appear to be JSON: %r" % s)[
+                           :77] + "...") from e
     return nb_dict
 
 # High level API
 
+
 def get_version(nb):
     """Get the version of a notebook.
 
@@ -53,24 +57,25 @@ def reads(s, **kwargs):
     -------
     nb : NotebookNode
         The notebook that was read.
-    
+
     Raises
     ------
     ValidationError 
         Notebook JSON for a given version is missing an expected key and cannot be read.
-    
+
     NBFormatError
         Specified major version is invalid or unsupported.
     """
     from . import versions, NBFormatError
-    
+
     nb_dict = parse_json(s, **kwargs)
     (major, minor) = get_version(nb_dict)
     if major in versions:
         try:
             return versions[major].to_notebook_json(nb_dict, minor=minor)
         except AttributeError as e:
-            raise ValidationError(f"The notebook is invalid and is missing an expected key: {e}")
+            raise ValidationError(
+                f"The notebook is invalid and is missing an expected key: {e}")
     else:
         raise NBFormatError('Unsupported nbformat version %s' % major)
 
@@ -92,4 +97,3 @@ def read(fp, **kwargs):
         The notebook that was read.
     """
     return reads(fp.read(), **kwargs)
-
diff --git a/nbformat/v3/rwbase.py b/nbformat/v3/rwbase.py
index a433df4c..3b19af57 100644
--- a/nbformat/v3/rwbase.py
+++ b/nbformat/v3/rwbase.py
@@ -23,11 +23,14 @@ def restore_bytes(nb):
                         if "png" in output:
                             output.png = output.png.encode("ascii", "replace")
                         if "jpeg" in output:
-                            output.jpeg = output.jpeg.encode("ascii", "replace")
+                            output.jpeg = output.jpeg.encode(
+                                "ascii", "replace")
     except KeyError as e:
-        raise validator.ValidationError(f"The notebook was invalid missing the key: {e.message}")
+        raise validator.ValidationError(
+            f"The notebook was invalid missing the key: {e.message}")
     return nb
 
+
 # output keys that are likely to have multiline values
 _multiline_outputs = ['text', 'html', 'svg', 'latex', 'javascript', 'json']
 
@@ -67,7 +70,7 @@ def rejoin_lines(nb):
                         item = output.get(key, None)
                         if isinstance(item, list):
                             output[key] = _join_lines(item)
-            else: # text, heading cell
+            else:  # text, heading cell
                 for key in ['source', 'rendered']:
                     item = cell.get(key, None)
                     if isinstance(item, list):
@@ -93,7 +96,7 @@ def split_lines(nb):
                         item = output.get(key, None)
                         if isinstance(item, str):
                             output[key] = item.splitlines(True)
-            else: # text, heading cell
+            else:  # text, heading cell
                 for key in ['source', 'rendered']:
                     item = cell.get(key, None)
                     if isinstance(item, str):
@@ -103,6 +106,7 @@ def split_lines(nb):
 # b64 encode/decode are never actually used, because all bytes objects in
 # the notebook are already b64-encoded, and we don't need/want to double-encode
 
+
 def base64_decode(nb):
     """Restore all bytes objects in the notebook from base64-encoded strings.
 
@@ -179,8 +183,5 @@ def writes(self, nb, **kwargs):
 
     def write(self, nb, fp, **kwargs):
         """Write a notebook to a file like object"""
-        nbs = self.writes(nb,**kwargs)
+        nbs = self.writes(nb, **kwargs)
         return fp.write(nbs)
-
-
-