gh-36032: Fix pycodestyle warning E721
    
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Fix the warnings coming from pycodestyle E721, "E721 do not compare
types, for exact checks use `is` / `is not`, for instance checks use
`isinstance()`".

<!-- Describe your changes here in detail -->

Mostly I've made changes like `type(x) == type(y)` to `type(x) is
type(y)`, also adding some uses of `isinstance`. When I run `pycodestyle
--select=E721 --statistics src/sage/` I now get no hits.

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URL: #36032
Reported by: John H. Palmieri
Reviewer(s): Matthias Köppe

Author: Release Manager

src/sage/algebras/hecke_algebras/cubic_hecke_base_ring.py

@@ -59,9 +59,9 @@ def normalize_names_markov(names, markov_trace_version):
     if markov_trace_version:
         names = normalize_names(4, names)
     else:
-        if type(names) == tuple:
+        if isinstance(names, tuple):
             names = list(names)
-        if type(names) == list and len(names) > 3:
+        if isinstance(names, list) and len(names) > 3:
             names = normalize_names(3, names[0:3])
         else:
             names = normalize_names(3, names)
@@ -641,10 +641,10 @@ def create_specialization(self, im_cubic_equation_roots, im_writhe_parameter=Non
         # corresponding specialized extension ring.
         # ----------------------------------------------------------------------
 
-        if type(im_cubic_equation_roots) == tuple:
+        if isinstance(im_cubic_equation_roots, tuple):
             im_cubic_equation_roots = list(im_cubic_equation_roots)
 
-        if type(im_cubic_equation_roots) != list:
+        if not isinstance(im_cubic_equation_roots, list):
             raise TypeError('cubic_equation_roots must be a list of three elements')
 
         if len(im_cubic_equation_roots) != 3:
@@ -1226,10 +1226,10 @@ def create_specialization(self, im_cubic_equation_parameters, im_writhe_paramete
         # ----------------------------------------------------------------------
         # setting the base_ring  according to the cubic_equation_parameters
         # ----------------------------------------------------------------------
-        if type(im_cubic_equation_parameters) == tuple:
+        if isinstance(im_cubic_equation_parameters, tuple):
             im_cubic_equation_parameters = list(im_cubic_equation_parameters)
 
-        if type(im_cubic_equation_parameters) != list:
+        if not isinstance(im_cubic_equation_parameters, list):
             raise TypeError('cubic_equation_parameters must be a list of three elements')
 
         if len(im_cubic_equation_parameters) != 3:

src/sage/algebras/quantum_groups/quantum_group_gap.py

@@ -1161,7 +1161,7 @@ def __richcmp__(self, other, op):
             False
         """
         if op == op_EQ:
-            return (type(self) == type(other)
+            return (type(self) is type(other)
                     and self.domain() is other.domain()
                     and self._im_gens == other._im_gens)
         if op == op_NE:

src/sage/categories/pushout.py

@@ -202,7 +202,7 @@ def __eq__(self, other):
             sage: I == I        # indirect doctest
             True
         """
-        return type(self) == type(other)
+        return type(self) is type(other)
 
     def __ne__(self, other):
         """
@@ -525,7 +525,7 @@ def __eq__(self, other):
         if isinstance(other, CompositeConstructionFunctor):
             return self.all == other.all
         else:
-            return type(self) == type(other)
+            return type(self) is type(other)
 
     def __ne__(self, other):
         """
@@ -677,7 +677,7 @@ def __eq__(self, other):
             sage: I == QQ.construction()[0]
             False
         """
-        c = (type(self) == type(other))
+        c = (type(self) is type(other))
         if not c:
             if isinstance(other, IdentityFunctor_generic):
                 return True
@@ -2986,7 +2986,7 @@ def __eq__(self, other):
         """
         if not isinstance(other, QuotientFunctor):
             return False
-        return (type(self) == type(other) and
+        return (type(self) is type(other) and
                 self.domain() == other.domain() and
                 self.codomain() == other.codomain() and
                 self.names == other.names and

src/sage/combinat/growth.py

@@ -1128,7 +1128,7 @@ def __eq__(self, other):
             sage: G1 == G2
             False
         """
-        return (type(self) == type(other) and
+        return (type(self) is type(other) and
                 self.rule == other.rule and
                 self._lambda == other._lambda and
                 self._mu == other._mu and

src/sage/combinat/recognizable_series.py

@@ -2095,7 +2095,7 @@ def _element_constructor_(self, data,
         if isinstance(data, int) and data == 0:
             return self._zero_()
 
-        if type(data) == self.element_class and data.parent() == self:
+        if isinstance(data, self.element_class) and data.parent() == self:
             element = data
 
         elif isinstance(data, RecognizableSeries):

src/sage/combinat/words/paths.py

@@ -455,7 +455,7 @@ def __eq__(self, other):
             sage: W1 == W3
             False
         """
-        return self is other or (type(self) == type(other) and
+        return self is other or (type(self) is type(other) and
             self.alphabet() == other.alphabet() and
             self.vector_space() == other.vector_space() and
             self.letters_to_steps() == other.letters_to_steps())

src/sage/doctest/sources.py

@@ -159,7 +159,7 @@ def __eq__(self, other):
             sage: FDS == FDS2
             True
         """
-        if type(self) != type(other):
+        if type(self) is not type(other):
             return False
         return self.__dict__ == other.__dict__
 

src/sage/dynamics/complex_dynamics/mandel_julia.py

@@ -396,7 +396,7 @@ def external_ray(theta, **kwds):
             pixel[i, j] = old_pixel[i, j]
 
     # Make sure that theta is a list so loop below works
-    if type(theta) != list:
+    if not isinstance(theta, list):
         theta = [theta]
 
     # Check if theta is in the interval [0,1]

src/sage/geometry/cone.py

@@ -844,7 +844,7 @@ def __richcmp__(self, right, op):
             sage: c2 is c3
             False
         """
-        if type(self) != type(right):
+        if type(self) is not type(right):
             return NotImplemented
 
         # We probably do need to have explicit comparison of lattices here

src/sage/geometry/relative_interior.py

@@ -337,7 +337,7 @@ def __eq__(self, other):
             sage: ri_segment == empty
             False
         """
-        if type(self) != type(other):
+        if type(self) is not type(other):
             return False
         return self._polyhedron == other._polyhedron