gh-36192: fix E228 then E225 in rings/
    
fix pycodestyle warnings E228 and E225 in rings

done using autopep8

### 📝 Checklist

- [x] The title is concise, informative, and self-explanatory.
- [x] The description explains in detail what this PR is about.
    
URL: #36192
Reported by: Frédéric Chapoton
Reviewer(s): Frédéric Chapoton, Kwankyu Lee

Author: Release Manager

src/sage/rings/asymptotic/asymptotics_multivariate_generating_functions.py

@@ -823,7 +823,7 @@ def univariate_decomposition(self):
         for a, m in df:
             am = a**m
             q, r = denominator.quo_rem(am)
-            assert r==0
+            assert r == 0
             numer = p * q.inverse_mod(am) % am
             # The inverse exists because the product and a**m
             # are relatively prime.
@@ -1930,7 +1930,7 @@ def asymptotics_smooth(self, p, alpha, N, asy_var, coordinate=None,
             if v.mod(2) == 0:
                 At_derivs = diff_all(At, T, 2 * N - 2, sub=hderivs1,
                                      sub_final=[Tstar, atP], rekey=AA)
-                Phitu_derivs = diff_all(Phitu, T, 2 * N - 2 +v,
+                Phitu_derivs = diff_all(Phitu, T, 2 * N - 2 + v,
                                         sub=hderivs1, sub_final=[Tstar, atP],
                                         zero_order=v + 1, rekey=BB)
             else:

src/sage/rings/complex_interval_field.py

@@ -558,7 +558,7 @@ def _repr_(self):
             sage: ComplexIntervalField(100) # indirect doctest
             Complex Interval Field with 100 bits of precision
         """
-        return "Complex Interval Field with %s bits of precision"%self._prec
+        return "Complex Interval Field with %s bits of precision" % self._prec
 
     def _latex_(self):
         r"""

src/sage/rings/finite_rings/conway_polynomials.py

@@ -471,7 +471,7 @@ def find_leveller(qindex, level, x, xleveled, searched, i):
         searched[i] = True
         crt_possibles = []
         for j in range(1,len(qlist)):
-            if i==j:
+            if i == j:
                 continue
             if crt[(i,j)][qindex][1] >= level:
                 if xleveled[j]:
@@ -487,7 +487,7 @@ def find_leveller(qindex, level, x, xleveled, searched, i):
 
     def propagate_levelling(qindex, level, x, xleveled, i):
         for j in range(1, len(qlist)):
-            if i==j:
+            if i == j:
                 continue
             if not xleveled[j] and crt[(i,j)][qindex][1] >= level:
                 newxj = x[i][0] + crt[(i,j)][qindex][0]

src/sage/rings/finite_rings/finite_field_givaro.py

@@ -510,7 +510,7 @@ def _pari_modulus(self):
             Mod(1, 3)*a^4 + Mod(2, 3)*a^3 + Mod(2, 3)
         """
         f = pari(str(self.modulus()))
-        return f.subst('x', 'a') * pari("Mod(1,%s)"%self.characteristic())
+        return f.subst('x', 'a') * pari("Mod(1,%s)" % self.characteristic())
 
     def __iter__(self):
         """

src/sage/rings/finite_rings/finite_field_ntl_gf2e.py

@@ -305,4 +305,4 @@ def _pari_modulus(self):
             Mod(1, 2)*a^16 + Mod(1, 2)*a^5 + Mod(1, 2)*a^3 + Mod(1, 2)*a^2 + Mod(1, 2)
         """
         f = pari(str(self.modulus()))
-        return f.subst('x', 'a') * pari("Mod(1,%s)"%self.characteristic())
+        return f.subst('x', 'a') * pari("Mod(1,%s)" % self.characteristic())

src/sage/rings/finite_rings/homset.py

@@ -153,9 +153,9 @@ def _repr_(self):
         D = self.domain()
         C = self.codomain()
         if C == D:
-            return "Automorphism group of %s"%D
+            return "Automorphism group of %s" % D
         else:
-            return "Set of field embeddings from %s to %s"%(D, C)
+            return "Set of field embeddings from %s to %s" % (D, C)
 
     def is_aut(self):
         """

src/sage/rings/function_field/constructor.py

@@ -86,7 +86,7 @@ def create_key(self, F, names):
             sage: K.<x> = FunctionField(QQ) # indirect doctest
         """
         if not isinstance(names, tuple):
-            names=(names,)
+            names = (names,)
         return (F, names)
 
     def create_object(self, version, key,**extra_args):
@@ -112,7 +112,7 @@ def create_object(self, version, key,**extra_args):
             return RationalFunctionField(key[0], names=key[1])
 
 
-FunctionField=FunctionFieldFactory("sage.rings.function_field.constructor.FunctionField")
+FunctionField = FunctionFieldFactory("sage.rings.function_field.constructor.FunctionField")
 
 
 class FunctionFieldExtensionFactory(UniqueFactory):
@@ -171,9 +171,9 @@ def create_key(self,polynomial,names):
 
         """
         if names is None:
-            names=polynomial.variable_name()
+            names = polynomial.variable_name()
         if not isinstance(names,tuple):
-            names=(names,)
+            names = (names,)
         return (polynomial,names,polynomial.base_ring())
 
     def create_object(self,version,key,**extra_args):

src/sage/rings/function_field/divisor.py

@@ -1023,7 +1023,7 @@ def _repr_(self):
             sage: F.divisor_group()
             Divisor group of Function field in y defined by y^2 + 4*x^3 + 4
         """
-        return "Divisor group of %s"%(self._field,)
+        return "Divisor group of %s" % (self._field,)
 
     def _element_constructor_(self, x):
         """

src/sage/rings/function_field/function_field_polymod.py

@@ -280,7 +280,7 @@ def _to_base_field(self, f):
         K = self.base_field()
         if f.element().is_constant():
             return K(f.element())
-        raise ValueError("%r is not an element of the base field"%(f,))
+        raise ValueError("%r is not an element of the base field" % (f,))
 
     def _to_constant_base_field(self, f):
         """
@@ -572,7 +572,7 @@ def _repr_(self):
             sage: L._repr_()
             'Function field in y defined by y^5 - 2*x*y + (-x^4 - 1)/x'
         """
-        return "Function field in %s defined by %s"%(self.variable_name(), self._polynomial)
+        return "Function field in %s defined by %s" % (self.variable_name(), self._polynomial)
 
     def base_field(self):
         """

src/sage/rings/function_field/function_field_rational.py

@@ -220,7 +220,7 @@ def _repr_(self):
             sage: K._repr_()
             'Rational function field in t over Rational Field'
         """
-        return "Rational function field in %s over %s"%(
+        return "Rational function field in %s over %s" % (
             self.variable_name(), self._constant_field)
 
     def _element_constructor_(self, x):
@@ -304,7 +304,7 @@ def _to_constant_base_field(self, f):
             # When K is not exact, f.denominator() might not be an exact 1, so
             # we need to divide explicitly to get the correct precision
             return K(f.numerator()) / K(f.denominator())
-        raise ValueError("only constants can be converted into the constant base field but %r is not a constant"%(f,))
+        raise ValueError("only constants can be converted into the constant base field but %r is not a constant" % (f,))
 
     def _to_polynomial(self, f):
         """
@@ -349,7 +349,7 @@ def _to_bivariate_polynomial(self, f):
         v = f.list()
         denom = lcm([a.denominator() for a in v])
         S = denom.parent()
-        x,t = S.base_ring()['%s,%s'%(f.parent().variable_name(),self.variable_name())].gens()
+        x,t = S.base_ring()['%s,%s' % (f.parent().variable_name(),self.variable_name())].gens()
         phi = S.hom([t])
         return sum([phi((denom * v[i]).numerator()) * x**i for i in range(len(v))]), denom