replace some class' base class with InheritComparisonUniqueRepresenta…

…tion where possible

src/sage/algebras/clifford_algebra.py

@@ -17,9 +17,9 @@
 #*****************************************************************************
 from six import iteritems
 
-from sage.misc.six import with_metaclass
 from sage.misc.cachefunc import cached_method
-from sage.structure.unique_representation import UniqueRepresentation
+from sage.structure.unique_representation import (
+        InheritComparisonUniqueRepresentation)
 from copy import copy
 
 from sage.categories.algebras_with_basis import AlgebrasWithBasis
@@ -35,7 +35,6 @@
 from sage.combinat.subset import SubsetsSorted
 from sage.quadratic_forms.quadratic_form import QuadraticForm
 from sage.algebras.weyl_algebra import repr_from_monomials
-from sage.misc.inherit_comparison import InheritComparisonClasscallMetaclass
 
 
 class CliffordAlgebraElement(CombinatorialFreeModule.Element):
@@ -2161,10 +2160,8 @@ def scalar(self, other):
 #####################################################################
 ## Differentials
 
-class ExteriorAlgebraDifferential(with_metaclass(
-        InheritComparisonClasscallMetaclass,
-        ModuleMorphismByLinearity, UniqueRepresentation
-    )):
+class ExteriorAlgebraDifferential(ModuleMorphismByLinearity,
+                                  InheritComparisonUniqueRepresentation):
     r"""
     Internal class to store the data of a boundary or coboundary of
     an exterior algebra `\Lambda(L)` defined by the structure

src/sage/algebras/commutative_dga.py

@@ -74,11 +74,10 @@
 from __future__ import print_function, absolute_import
 from six import string_types
 
-from sage.misc.six import with_metaclass
-from sage.structure.unique_representation import UniqueRepresentation
+from sage.structure.unique_representation import (
+        InheritComparisonUniqueRepresentation, UniqueRepresentation)
 from sage.structure.sage_object import SageObject
 from sage.misc.cachefunc import cached_method
-from sage.misc.inherit_comparison import InheritComparisonClasscallMetaclass
 from sage.misc.functional import is_odd, is_even
 from sage.misc.misc_c import prod
 from sage.categories.algebras import Algebras
@@ -99,10 +98,7 @@
 from sage.rings.quotient_ring_element import QuotientRingElement
 
 
-class Differential(with_metaclass(
-        InheritComparisonClasscallMetaclass,
-        UniqueRepresentation, Morphism
-    )):
+class Differential(InheritComparisonUniqueRepresentation, Morphism):
     r"""
     Differential of a commutative graded algebra.
 
@@ -935,7 +931,7 @@ def _repr_(self):
             sage: A
             Graded Commutative Algebra with generators ('x', 'y', 'z', 't') in degrees (3, 4, 2, 1) over Rational Field
             sage: A.quotient(A.ideal(3*x*z - 2*y*t))
-            Graded Commutative Algebra with generators ('x', 'y', 'z', 't') in degrees (3, 4, 2, 1) with relations [3*x*z - 2*y*t] over Rational Field 
+            Graded Commutative Algebra with generators ('x', 'y', 'z', 't') in degrees (3, 4, 2, 1) with relations [3*x*z - 2*y*t] over Rational Field
         """
         s = "Graded Commutative Algebra with generators {} in degrees {}".format(self._names, self._degrees)
         # Find any nontrivial relations.

src/sage/modular/modform_hecketriangle/graded_ring_element.py

@@ -17,7 +17,6 @@
 #                  http://www.gnu.org/licenses/
 #*****************************************************************************
 
-from sage.misc import six
 from sage.rings.all import ZZ, infinity, LaurentSeries, O
 from sage.functions.all import exp
 from sage.rings.number_field.number_field import QuadraticField
@@ -26,13 +25,13 @@
 from sage.structure.parent_gens import localvars
 from sage.structure.richcmp import op_NE, op_EQ
 from sage.structure.element import CommutativeAlgebraElement
-from sage.structure.unique_representation import UniqueRepresentation
+from sage.structure.unique_representation import (
+        InheritComparisonUniqueRepresentation)
 
 from sage.modules.free_module_element import vector
 from sage.geometry.hyperbolic_space.hyperbolic_interface import HyperbolicPlane
 
 from sage.misc.cachefunc import cached_method
-from sage.misc.inherit_comparison import InheritComparisonClasscallMetaclass
 
 from .constructor import rational_type, FormsSpace, FormsRing
 from .series_constructor import MFSeriesConstructor
@@ -42,10 +41,8 @@
 # corresponding operations (e.g. __pow__) even though the category
 # (and class) of the parent is in some cases not
 # CommutativeAlgebras but Modules
-class FormsRingElement(six.with_metaclass(
-        InheritComparisonClasscallMetaclass,
-        CommutativeAlgebraElement, UniqueRepresentation
-    )):
+class FormsRingElement(CommutativeAlgebraElement,
+                       InheritComparisonUniqueRepresentation):
     r"""
     Element of a FormsRing.
     """