let shorthands be tuple and immutable

src/sage/algebras/iwahori_hecke_algebra.py

@@ -481,16 +481,17 @@ def __init__(self, W, q1, q2, base_ring):
             # Attach the generic Hecke algebra and the basis change maps
             self._root = root
             self._generic_iwahori_hecke_algebra = IwahoriHeckeAlgebra_nonstandard(W)
-            self._shorthands = ['C', 'Cp', 'T']
+            self._shorthands = ('C', 'Cp', 'T')
         else:
             # Can we actually remove the bases C and Cp in this case?
             self._root = None
-            self._shorthands = ['T']
+            self._shorthands = ('T',)
 
         # if 2 is a unit in the base ring then add th A and B bases
         try:
             base_ring(base_ring.one() / 2)
-            self._shorthands.extend(['A', 'B'])
+            sh = self._shorthands
+            self._shorthands = (*sh, 'A', 'B')
         except (TypeError, ZeroDivisionError):
             pass
 
@@ -2785,7 +2786,7 @@ def __init__(self, W):
         self.u_inv = normalized_laurent_polynomial(base_ring, u**-1)
         self.v_inv = normalized_laurent_polynomial(base_ring, v**-1)
 
-        self._shorthands = ['C', 'Cp', 'T']
+        self._shorthands = ('C', 'Cp', 'T',)
 
         if W.is_finite():
             self._category = FiniteDimensionalAlgebrasWithBasis(base_ring)

src/sage/categories/examples/with_realizations.py

@@ -197,7 +197,7 @@ def __init__(self, R, S):
         F_to_Out   .register_as_coercion()
         (~F_to_Out).register_as_coercion()
 
-    _shorthands = ["F", "In", "Out"]
+    _shorthands = ("F", "In", "Out")
 
     def a_realization(self):
         r"""

src/sage/combinat/chas/fsym.py

@@ -495,7 +495,7 @@ def __init__(self, base_ring):
         cat = HopfAlgebras(base_ring).Graded().Connected()
         Parent.__init__(self, base=base_ring, category=cat.WithRealizations())
 
-    _shorthands = ['G']
+    _shorthands = ('G',)
 
     def a_realization(self):
         r"""
@@ -790,7 +790,7 @@ class FreeSymmetricFunctions_Dual(UniqueRepresentation, Parent):
         sage: TF(F[[5, 1, 4, 2, 3]])
         F[135|2|4]
     """
-    def __init__(self, base_ring):
+    def __init__(self, base_ring) -> None:
         r"""
         Initialize ``self``.
 
@@ -802,7 +802,7 @@ def __init__(self, base_ring):
         cat = HopfAlgebras(base_ring).Graded().Connected()
         Parent.__init__(self, base=base_ring, category=cat.WithRealizations())
 
-    _shorthands = ['F']
+    _shorthands = ('F',)
 
     def a_realization(self):
         r"""

src/sage/combinat/chas/wqsym.py

@@ -498,7 +498,7 @@ def a_realization(self):
         """
         return self.M()
 
-    _shorthands = tuple(['M', 'X', 'C', 'Q', 'Phi'])
+    _shorthands = ('M', 'X', 'C', 'Q', 'Phi')
 
     # add options to class
     class options(GlobalOptions):

src/sage/combinat/fqsym.py

@@ -400,7 +400,7 @@ def a_realization(self):
         """
         return self.F()
 
-    _shorthands = tuple(['F', 'G', 'M'])
+    _shorthands = ('F', 'G', 'M')
 
     class F(FQSymBasis_abstract):
         r"""

src/sage/combinat/ncsf_qsym/ncsf.py

@@ -403,7 +403,7 @@ class NonCommutativeSymmetricFunctions(UniqueRepresentation, Parent):
         sage: TestSuite(complete).run()
     """
 
-    def __init__(self, R):
+    def __init__(self, R) -> None:
         r"""
         TESTS::
 
@@ -445,7 +445,7 @@ def __init__(self, R):
         Phi.algebra_morphism(Phi._to_complete_on_generators,
                              codomain=complete).register_as_coercion()
 
-    def _repr_(self): # could be taken care of by the category
+    def _repr_(self) -> str:  # could be taken care of by the category
         r"""
         EXAMPLES::
 
@@ -472,7 +472,8 @@ def a_realization(self):
         """
         return self.complete()
 
-    _shorthands = tuple(['S', 'R', 'L', 'Phi', 'Psi', 'nM', 'I', 'dQS', 'dYQS', 'ZL', 'ZR'])
+    _shorthands = ('S', 'R', 'L', 'Phi', 'Psi', 'nM', 'I',
+                   'dQS', 'dYQS', 'ZL', 'ZR')
 
     def dual(self):
         r"""

src/sage/combinat/ncsf_qsym/qsym.py

@@ -546,7 +546,7 @@ class QuasiSymmetricFunctions(UniqueRepresentation, Parent):
         True
     """
 
-    def __init__(self, R):
+    def __init__(self, R) -> None:
         """
         The Hopf algebra of quasi-symmetric functions.
         See ``QuasiSymmetricFunctions`` for full documentation.
@@ -609,7 +609,7 @@ def __init__(self, R):
                                              codomain=Fundamental, category=category)
         Sym_s_to_F.register_as_coercion()
 
-    def _repr_(self):
+    def _repr_(self) -> str:
         r"""
         EXAMPLES::
 
@@ -632,7 +632,7 @@ def a_realization(self):
         """
         return self.Monomial()
 
-    _shorthands = tuple(['M', 'F', 'E', 'dI', 'QS', 'YQS', 'phi', 'psi'])
+    _shorthands = ('M', 'F', 'E', 'dI', 'QS', 'YQS', 'phi', 'psi')
 
     def dual(self):
         r"""

src/sage/combinat/ncsym/ncsym.py

@@ -293,7 +293,7 @@ class SymmetricFunctionsNonCommutingVariables(UniqueRepresentation, Parent):
         -4*p[] + 2*p[1] + p[2, 2]
     """
 
-    def __init__(self, R):
+    def __init__(self, R) -> None:
         """
         Initialize ``self``.
 
@@ -309,7 +309,7 @@ def __init__(self, R):
         category = GradedHopfAlgebras(R).Cocommutative()
         Parent.__init__(self, category=category.WithRealizations())
 
-    def _repr_(self):
+    def _repr_(self) -> str:
         r"""
         EXAMPLES::
 
@@ -331,7 +331,7 @@ def a_realization(self):
         """
         return self.powersum()
 
-    _shorthands = tuple(['chi', 'cp', 'm', 'e', 'h', 'p', 'rho', 'x'])
+    _shorthands = ('chi', 'cp', 'm', 'e', 'h', 'p', 'rho', 'x')
 
     def dual(self):
         r"""

src/sage/combinat/sf/sf.py

@@ -1430,8 +1430,8 @@ def register_isomorphism(self, morphism, only_conversion=False):
         else:
             morphism.codomain().register_coercion(morphism)
 
-    _shorthands = ['e', 'f', 'h', 'm', 'p', 's']
-    _shorthands_all = sorted(_shorthands + ['ht', 'o', 'sp', 'st', 'w'])
+    _shorthands = ('e', 'f', 'h', 'm', 'p', 's')
+    _shorthands_all = tuple(sorted(_shorthands + ('ht', 'o', 'sp', 'st', 'w')))
 
     def __init_extra__(self):
         """

src/sage/rings/polynomial/integer_valued_polynomials.py

@@ -75,7 +75,7 @@ class IntegerValuedPolynomialRing(UniqueRepresentation, Parent):
         ...
         TypeError: argument R must be a commutative ring
     """
-    def __init__(self, R):
+    def __init__(self, R) -> None:
         """
         TESTS::
 
@@ -88,7 +88,7 @@ def __init__(self, R):
         cat = Algebras(R).Commutative().WithBasis()
         Parent.__init__(self, base=R, category=cat.WithRealizations())
 
-    _shorthands = ["B", "S"]
+    _shorthands = ("B", "S")
 
     def _repr_(self) -> str:
         r"""

src/sage/rings/polynomial/q_integer_valued_polynomials.py

@@ -230,7 +230,7 @@ def __init__(self, R, q) -> None:
         cat = Algebras(R).Commutative().WithBasis()
         Parent.__init__(self, base=R, category=cat.WithRealizations())
 
-    _shorthands = ["B", "S"]
+    _shorthands = ("B", "S")
 
     def _repr_(self) -> str:
         r"""