diff --git a/graphene/pyutils/version.py b/graphene/pyutils/version.py
index a0b0d2ba..ed2d16b1 100644
--- a/graphene/pyutils/version.py
+++ b/graphene/pyutils/version.py
@@ -46,12 +46,11 @@ def get_complete_version(version=None):
         from graphene import VERSION as version
     else:
         raise_assertion_if_not(
-            condition=len(version) is 5,
-            message="Wrong tuple provided"
+            condition=len(version) is 5, message="Wrong tuple provided"
         )
         raise_assertion_if_not(
             condition=version[3] in ("alpha", "beta", "rc", "final"),
-            message="Version not correct."
+            message="Version not correct.",
         )
 
     return version
diff --git a/graphene/relay/connection.py b/graphene/relay/connection.py
index 968242ed..3a96a447 100644
--- a/graphene/relay/connection.py
+++ b/graphene/relay/connection.py
@@ -55,7 +55,7 @@ class Connection(ObjectType):
         _meta = ConnectionOptions(cls)
         raise_assertion_if_not(
             condition=node,
-            message="You have to provide a node in {}.Meta".format(cls.__name__)
+            message="You have to provide a node in {}.Meta".format(cls.__name__),
         )
         raise_assertion_if_not(
             condition=issubclass(
@@ -63,7 +63,7 @@ class Connection(ObjectType):
             ),
             message=('Received incompatible node "{}" for Connection {}.').format(
                 node, cls.__name__
-            )
+            ),
         )
 
         base_name = re.sub("Connection$", "", name or cls.__name__) or node._meta.name
@@ -143,7 +143,7 @@ class IterableConnectionField(Field):
             condition=issubclass(connection_type, Connection),
             message='{} type have to be a subclass of Connection. Received "{}".'.format(
                 self.__class__.__name__, connection_type
-            )
+            ),
         )
         return type
 
@@ -159,7 +159,7 @@ class IterableConnectionField(Field):
                 Received "{}"
             """.format(
                 connection_type, resolved
-            )
+            ),
         )
 
         connection = connection_from_list(
diff --git a/graphene/relay/mutation.py b/graphene/relay/mutation.py
index 23e0f655..792230c7 100644
--- a/graphene/relay/mutation.py
+++ b/graphene/relay/mutation.py
@@ -17,14 +17,10 @@ class ClientIDMutation(Mutation):
         input_class = getattr(cls, "Input", None)
         base_name = re.sub("Payload$", "", name or cls.__name__)
 
-        raise_assertion_if_not(
-            condition=not output,
-            message="Can't specify any output"
-        )
+        raise_assertion_if_not(condition=not output, message="Can't specify any output")
 
         raise_assertion_if_not(
-            condition=not arguments,
-            message="Can't specify any arguments"
+            condition=not arguments, message="Can't specify any arguments"
         )
 
         bases = (InputObjectType,)
@@ -50,10 +46,8 @@ class ClientIDMutation(Mutation):
         if cls.mutate and cls.mutate.__func__ == ClientIDMutation.mutate.__func__:
             raise_assertion_if_not(
                 condition=mutate_and_get_payload,
-                message="{name}.mutate_and_get_payload method is required" \
-                        " in a ClientIDMutation.".format(
-                            name=name or cls.__name__
-                )
+                message="{name}.mutate_and_get_payload method is required"
+                " in a ClientIDMutation.".format(name=name or cls.__name__),
             )
 
         if not name:
diff --git a/graphene/relay/node.py b/graphene/relay/node.py
index 50c1fccb..d9c4c0f6 100644
--- a/graphene/relay/node.py
+++ b/graphene/relay/node.py
@@ -7,7 +7,6 @@ from graphql_relay import from_global_id, to_global_id
 from ..types import ID, Field, Interface, ObjectType
 from ..types.interface import InterfaceOptions
 from ..types.utils import get_type
-from ..utils.comparison_helper import raise_assertion_if_not
 
 
 def is_node(objecttype):
diff --git a/graphene/types/argument.py b/graphene/types/argument.py
index e34133bb..11a37767 100644
--- a/graphene/types/argument.py
+++ b/graphene/types/argument.py
@@ -76,9 +76,7 @@ def to_arguments(args, extra_args=None):
         arg_name = default_name or arg.name
         raise_assertion_if_not(
             condition=arg_name not in arguments,
-            message='More than one Argument have same name "{}".'.format(
-                arg_name
-            )
+            message='More than one Argument have same name "{}".'.format(arg_name),
         )
         arguments[arg_name] = arg
 
diff --git a/graphene/types/base.py b/graphene/types/base.py
index a2d74509..852737bf 100644
--- a/graphene/types/base.py
+++ b/graphene/types/base.py
@@ -33,8 +33,7 @@ class BaseType(SubclassWithMeta):
     @classmethod
     def __init_subclass_with_meta__(cls, name=None, description=None, _meta=None):
         raise_assertion_if_not(
-            condition="_meta" not in cls.__dict__,
-            message="Can't assign directly meta"
+            condition="_meta" not in cls.__dict__, message="Can't assign directly meta"
         )
         if not _meta:
             return
diff --git a/graphene/types/datetime.py b/graphene/types/datetime.py
index f7f60519..61d42b75 100644
--- a/graphene/types/datetime.py
+++ b/graphene/types/datetime.py
@@ -22,7 +22,7 @@ class Date(Scalar):
             date = date.date()
         raise_assertion_if_not(
             condition=isinstance(date, datetime.date),
-            message='Received not compatible date "{}"'.format(repr(date))
+            message='Received not compatible date "{}"'.format(repr(date)),
         )
         return date.isoformat()
 
@@ -50,7 +50,7 @@ class DateTime(Scalar):
     def serialize(dt):
         raise_assertion_if_not(
             condition=isinstance(dt, (datetime.datetime, datetime.date)),
-            message='Received not compatible datetime "{}"'.format(repr(dt))
+            message='Received not compatible datetime "{}"'.format(repr(dt)),
         )
         return dt.isoformat()
 
@@ -78,8 +78,8 @@ class Time(Scalar):
     def serialize(time):
         raise_assertion_if_not(
             condition=isinstance(time, datetime.time),
-            message='Received not compatible time "{}"'.format(repr(time))
-        ) 
+            message='Received not compatible time "{}"'.format(repr(time)),
+        )
         return time.isoformat()
 
     @classmethod
diff --git a/graphene/types/field.py b/graphene/types/field.py
index 3582a242..e0e009a2 100644
--- a/graphene/types/field.py
+++ b/graphene/types/field.py
@@ -39,19 +39,19 @@ class Field(MountedType):
             condition=not args or isinstance(args, Mapping),
             message='Arguments in a field have to be a mapping, received "{}".'.format(
                 args
-            )
+            ),
         )
 
         raise_assertion_if_not(
-            condition=not(source and resolver),
-            message="A Field cannot have a source and a resolver in at the same time."
+            condition=not (source and resolver),
+            message="A Field cannot have a source and a resolver in at the same time.",
         )
 
         raise_assertion_if_not(
             condition=not callable(default_value),
             message='The default value can not be a function but received "{}".'.format(
                 base_type(default_value)
-            )
+            ),
         )
 
         if required:
diff --git a/graphene/types/mountedtype.py b/graphene/types/mountedtype.py
index e5eaa35c..bef31add 100644
--- a/graphene/types/mountedtype.py
+++ b/graphene/types/mountedtype.py
@@ -11,7 +11,7 @@ class MountedType(OrderedType):
         """
         raise_assertion_if_not(
             condition=isinstance(unmounted, UnmountedType),
-            message="{} can't mount {}".format(cls.__name__, repr(unmounted))
+            message="{} can't mount {}".format(cls.__name__, repr(unmounted)),
         )
 
         return cls(
diff --git a/graphene/types/mutation.py b/graphene/types/mutation.py
index f71d3d08..76486e9f 100644
--- a/graphene/types/mutation.py
+++ b/graphene/types/mutation.py
@@ -65,8 +65,8 @@ class Mutation(ObjectType):
             mutate = getattr(cls, "mutate", None)
             raise_assertion_if_not(
                 condition=mutate,
-                message="All mutations must define a mutate method in it"
-            ) 
+                message="All mutations must define a mutate method in it",
+            )
             resolver = get_unbound_function(mutate)
 
         if _meta.fields:
diff --git a/graphene/types/objecttype.py b/graphene/types/objecttype.py
index 140dd076..08e765cc 100644
--- a/graphene/types/objecttype.py
+++ b/graphene/types/objecttype.py
@@ -44,7 +44,7 @@ class ObjectType(BaseType):
                 condition=issubclass(interface, Interface),
                 message='All interfaces of {} must be a subclass of Interface. Received "{}".'.format(
                     cls.__name__, interface
-                )
+                ),
             )
             fields.update(interface._meta.fields)
 
@@ -53,11 +53,10 @@ class ObjectType(BaseType):
 
         raise_assertion_if_not(
             condition=not (possible_types and cls.is_type_of),
-            message=("{name}.Meta.possible_types will cause type collision with {name}.is_type_of. " \
-                "Please use one or other.".format(
-                    name=cls.__name__
-                )
-            )
+            message=(
+                "{name}.Meta.possible_types will cause type collision with {name}.is_type_of. "
+                "Please use one or other.".format(name=cls.__name__)
+            ),
         )
 
         if _meta.fields:
diff --git a/graphene/types/schema.py b/graphene/types/schema.py
index 39fee633..d9b86884 100644
--- a/graphene/types/schema.py
+++ b/graphene/types/schema.py
@@ -23,7 +23,7 @@ def assert_valid_root_type(_type):
     is_graphql_objecttype = isinstance(_type, GraphQLObjectType)
     raise_assertion_if_not(
         condition=is_graphene_objecttype or is_graphql_objecttype,
-        message="Type {} is not a valid ObjectType.".format(_type)
+        message="Type {} is not a valid ObjectType.".format(_type),
     )
 
 
@@ -59,7 +59,7 @@ class Schema(GraphQLSchema):
             condition=all(isinstance(d, GraphQLDirective) for d in directives),
             message="Schema directives must be List[GraphQLDirective] if provided but got: {}.".format(
                 directives
-            )
+            ),
         )
         self._directives = directives
         self.build_typemap()
diff --git a/graphene/types/structures.py b/graphene/types/structures.py
index f383e6cc..0647c5eb 100644
--- a/graphene/types/structures.py
+++ b/graphene/types/structures.py
@@ -72,7 +72,7 @@ class NonNull(Structure):
             condition=not isinstance(self._of_type, NonNull),
             message="Can only create NonNull of a Nullable GraphQLType but got: {}.".format(
                 self._of_type
-            )
+            ),
         )
 
     def __str__(self):
diff --git a/graphene/types/typemap.py b/graphene/types/typemap.py
index 25735613..93ea8ed9 100644
--- a/graphene/types/typemap.py
+++ b/graphene/types/typemap.py
@@ -63,13 +63,13 @@ def resolve_type(resolve_type_func, map, type_name, root, info):
         graphql_type = map.get(_type._meta.name)
         raise_assertion_if_not(
             condition=graphql_type,
-            message="Can't find type {} in schema".format(_type._meta.name)
+            message="Can't find type {} in schema".format(_type._meta.name),
         )
         raise_assertion_if_not(
             condition=graphql_type.graphene_type is _type,
             message="The type {} does not match with the associated graphene type {}.".format(
                 _type, graphql_type.graphene_type
-            )
+            ),
         )
         return graphql_type
 
@@ -105,7 +105,7 @@ class TypeMap(GraphQLTypeMap):
                     condition=_type.graphene_type is type,
                     message="Found different types with the same name in the schema: {}, {}.".format(
                         _type.graphene_type, type
-                    )
+                    ),
                 )
             return map
 
@@ -187,7 +187,7 @@ class TypeMap(GraphQLTypeMap):
                     condition=_type.graphene_type is type,
                     message="Found different types with the same name in the schema: {}, {}.".format(
                         _type.graphene_type, type
-                    )
+                    ),
                 )
             return _type
 
@@ -226,7 +226,7 @@ class TypeMap(GraphQLTypeMap):
                     condition=_type.graphene_type is type,
                     message="Found different types with the same name in the schema: {}, {}.".format(
                         _type.graphene_type, type
-                    )
+                    ),
                 )
             return _type
 
diff --git a/graphene/types/union.py b/graphene/types/union.py
index 5b3bfd96..a4f8d486 100644
--- a/graphene/types/union.py
+++ b/graphene/types/union.py
@@ -26,7 +26,7 @@ class Union(UnmountedType, BaseType):
     def __init_subclass_with_meta__(cls, types=None, **options):
         raise_assertion_if_not(
             condition=isinstance(types, (list, tuple)) and len(types) > 0,
-            message="Must provide types for Union {name}.".format(name=cls.__name__)
+            message="Must provide types for Union {name}.".format(name=cls.__name__),
         )
         _meta = UnionOptions(cls)
         _meta.types = types
diff --git a/graphene/types/uuid.py b/graphene/types/uuid.py
index d1f42683..4b40aa40 100644
--- a/graphene/types/uuid.py
+++ b/graphene/types/uuid.py
@@ -17,7 +17,7 @@ class UUID(Scalar):
             uuid = _UUID(uuid)
         raise_assertion_if_not(
             condition=isinstance(uuid, _UUID),
-            message="Expected UUID instance, received {}".format(uuid)
+            message="Expected UUID instance, received {}".format(uuid),
         )
         return str(uuid)
 
diff --git a/graphene/utils/annotate.py b/graphene/utils/annotate.py
index 9b8cb15c..d620356c 100644
--- a/graphene/utils/annotate.py
+++ b/graphene/utils/annotate.py
@@ -24,10 +24,10 @@ def annotate(_func=None, _trigger_warning=True, **annotations):
     # We make sure the annotations are valid
     for key, value in annotations.items():
         raise_assertion_if_not(
-            condition= key in func_signature.parameters,
+            condition=key in func_signature.parameters,
             message='The key {key} is not a function parameter in the function "{func_name}".'.format(
                 key=key, func_name=func_name(_func)
-            )
+            ),
         )
 
     func_annotations = getattr(_func, "__annotations__", None)
diff --git a/graphene/utils/subclass_with_meta.py b/graphene/utils/subclass_with_meta.py
index 5b4ff134..739e2147 100644
--- a/graphene/utils/subclass_with_meta.py
+++ b/graphene/utils/subclass_with_meta.py
@@ -7,7 +7,6 @@ from .props import props
 from .comparison_helper import raise_assertion_if_not
 
 
-
 class SubclassWithMeta_Meta(InitSubclassMeta):
     _meta = None
 
@@ -46,10 +45,10 @@ class SubclassWithMeta(six.with_metaclass(SubclassWithMeta_Meta)):
         if abstract:
             raise_assertion_if_not(
                 condition=not options,
-                message="Abstract types can only contain the abstract attribute. " \
-                    "Received: abstract, {option_keys}".format(
-                        option_keys=", ".join(options.keys())
-                )
+                message="Abstract types can only contain the abstract attribute. "
+                "Received: abstract, {option_keys}".format(
+                    option_keys=", ".join(options.keys())
+                ),
             )
         else:
             super_class = super(cls, cls)