gh-39393: breaking lines after else: in pyx files
    
as this is already done in all .py files and almost all pyx files

### 📝 Checklist

- [x] The title is concise and informative.
- [x] The description explains in detail what this PR is about.
    
URL: #39393
Reported by: Frédéric Chapoton
Reviewer(s): David Coudert, Kwankyu Lee

Author: Release Manager

src/sage/coding/binary_code.pyx

@@ -617,7 +617,7 @@ cdef codeword *expand_to_ortho_basis(BinaryCode B, int n) noexcept:
         i = k
         word = <codeword>1 << k
         k += 1
-    else: # NOTE THIS WILL NEVER HAPPEN AS CURRENTLY SET UP!
+    else:  # NOTE THIS WILL NEVER HAPPEN AS CURRENTLY SET UP!
         temp = (<codeword>1 << k) - 1
         i = k
         word = <codeword>1 << k
@@ -813,7 +813,7 @@ cdef class BinaryCode:
                     combination ^= (1 << j)
                     word ^= self_basis[j]
 
-        else: # isinstance(arg1, BinaryCode)
+        else:  # isinstance(arg1, BinaryCode)
             other_basis = other.basis
             for i from 0 <= i < nrows-1:
                 self_basis[i] = other_basis[i]
@@ -2423,9 +2423,12 @@ cdef class PartitionStack:
         cdef int *self_wd_lvls = self.wd_lvls
         cdef int *self_wd_ents = self.wd_ents
         while True:
-            if CG.is_one(self_wd_ents[wd_ptr], col): i += 1
-            if self_wd_lvls[wd_ptr] > k: wd_ptr += 1
-            else: break
+            if CG.is_one(self_wd_ents[wd_ptr], col):
+                i += 1
+            if self_wd_lvls[wd_ptr] > k:
+                wd_ptr += 1
+            else:
+                break
         return i
 
     def _wd_degree(self, C, wd, col_ptr, k):
@@ -3347,15 +3350,17 @@ cdef class BinaryCodeClassifier:
                 if qzb > 0: zb__Lambda_rho[k] = Lambda[k]
                 state = 3
 
-            elif state == 3: # attempt to rule out automorphisms while moving down the tree
+            elif state == 3:  # attempt to rule out automorphisms while moving down the tree
                 # if k > hzf, then we know that nu currently does not look like zeta, the first
                 # terminal node encountered, thus there is no automorphism to discover. If qzb < 0,
                 # i.e. Lambda[k] < zb[k], then the indicator is not maximal, and we can't reach a
                 # canonical leaf. If neither of these is the case, then proceed to state 4.
-                if hzf__h_zeta <= k or qzb >= 0: state = 4
-                else: state = 6
+                if hzf__h_zeta <= k or qzb >= 0:
+                    state = 4
+                else:
+                    state = 6
 
-            elif state == 4: # at this point we have -not- ruled out the presence of automorphisms
+            elif state == 4:  # at this point we have -not- ruled out the presence of automorphisms
                 if nu.is_discrete(k):
                     state = 7
                     continue  # we have a terminal node, so process it
@@ -3365,17 +3370,18 @@ cdef class BinaryCodeClassifier:
                 # equal to its minimum element
                 v[k] = nu.new_first_smallest_nontrivial(k, W, self.Phi_size * k)
                 if not nu.sat_225(k): hh = k + 1
-                e[k] = 0 # see state 12 and 17
-                state = 2 # continue down the tree
+                e[k] = 0  # see state 12 and 17
+                state = 2  # continue down the tree
 
-            elif state == 5: # same as state 3, but in the case where we haven't yet defined zeta
-                             # i.e. this is our first time down the tree. Once we get to the bottom,
-                             # we will have zeta = nu = rho, so we do:
+            elif state == 5:
+                # same as state 3, but in the case where we haven't yet defined zeta
+                # i.e. this is our first time down the tree. Once we get to the bottom,
+                # we will have zeta = nu = rho, so we do:
                 zf__Lambda_zeta[k] = Lambda[k]
                 zb__Lambda_rho[k] = Lambda[k]
                 state = 4
 
-            elif state == 6: # at this stage, there is no reason to continue downward, so backtrack
+            elif state == 6:  # at this stage, there is no reason to continue downward, so backtrack
                 j = k
 
                 # return to the longest ancestor nu[i] of nu that could have a
@@ -3396,9 +3402,10 @@ cdef class BinaryCodeClassifier:
                     else:
                         k = hh-1
                 # TODO: is the following line necessary?
-                if k == -1: k = 0
+                if k == -1:
+                    k = 0
 
-                if hb > k:# update hb since we are backtracking
+                if hb > k:  # update hb since we are backtracking
                     hb = k
                 # if j == hh, then all nodes lower than our current position are equivalent, so bail out
                 if j == hh:
@@ -3465,7 +3472,7 @@ cdef class BinaryCodeClassifier:
 
                 state = 10
 
-            elif state == 9: # nu is a better guess at the canonical label than rho
+            elif state == 9:  # nu is a better guess at the canonical label than rho
                 rho = PartitionStack(nu)
                 k_rho = k
                 qzb = 0
@@ -3475,7 +3482,7 @@ cdef class BinaryCodeClassifier:
                 zb__Lambda_rho[k+1] = -1
                 state = 6
 
-            elif state == 10: # we have an automorphism to process
+            elif state == 10:  # we have an automorphism to process
                 # increment l
                 if l < self.L-1: l += 1
                 # store information about the automorphism to Omega and Phi
@@ -3496,8 +3503,8 @@ cdef class BinaryCodeClassifier:
                         Omega[ii] ^= (1<<j)  # so cancel
                         j = col_gamma[j]     # cellmates
                     i += 1
-                    while i < ncols and not Omega[ii]&(1<<i): # find minimal element
-                        i += 1                                # of next cell
+                    while i < ncols and not Omega[ii]&(1<<i):  # find minimal element
+                        i += 1                                 # of next cell
                 i = 0
                 jj = self.radix
                 while i < nwords:

src/sage/libs/mpmath/ext_impl.pyx

@@ -1183,10 +1183,14 @@ cdef MPF_exp(MPF *y, MPF *x, MPopts opts):
     cdef mpz_t t, u
     cdef tuple w
     if x.special:
-        if x.special == S_ZERO: MPF_set_si(y, 1)
-        elif x.special == S_NINF: MPF_set_zero(y)
-        elif x.special == S_INF: MPF_set_inf(y)
-        else: MPF_set_nan(y)
+        if x.special == S_ZERO:
+            MPF_set_si(y, 1)
+        elif x.special == S_NINF:
+            MPF_set_zero(y)
+        elif x.special == S_INF:
+            MPF_set_inf(y)
+        else:
+            MPF_set_nan(y)
         return
     wp = opts.prec + 14
     sign = mpz_sgn(x.man) < 0

src/sage/libs/mpmath/utils.pyx

@@ -134,11 +134,15 @@ cpdef normalize(long sign, Integer man, exp, long bc, long prec, str rnd):
         elif rnd == 'd':
             mpz_fdiv_q_2exp(res.value, man.value, shift)
         elif rnd == 'f':
-            if sign: mpz_cdiv_q_2exp(res.value, man.value, shift)
-            else:    mpz_fdiv_q_2exp(res.value, man.value, shift)
+            if sign:
+                mpz_cdiv_q_2exp(res.value, man.value, shift)
+            else:
+                mpz_fdiv_q_2exp(res.value, man.value, shift)
         elif rnd == 'c':
-            if sign: mpz_fdiv_q_2exp(res.value, man.value, shift)
-            else:    mpz_cdiv_q_2exp(res.value, man.value, shift)
+            if sign:
+                mpz_fdiv_q_2exp(res.value, man.value, shift)
+            else:
+                mpz_cdiv_q_2exp(res.value, man.value, shift)
         elif rnd == 'u':
             mpz_cdiv_q_2exp(res.value, man.value, shift)
         exp += shift

src/sage/libs/singular/singular.pyx

@@ -96,16 +96,18 @@ cdef Rational si2sa_QQ(number *n, number **nn, ring *_ring):
 
     mpq_init(_z)
 
-    ##  Immediate integers handles carry the tag 'SR_INT', i.e. the last bit is 1.
-    ##  This distinguishes immediate integers from other handles which point to
-    ##  structures aligned on 4 byte boundaries and therefore have last bit zero.
-    ##  (The second bit is reserved as tag to allow extensions of this scheme.)
-    ##  Using immediates as pointers and dereferencing them gives address errors.
+    # Immediate integers handles carry the tag 'SR_INT', i.e. the last bit is 1.
+    # This distinguishes immediate integers from other handles which point to
+    # structures aligned on 4 byte boundaries and therefore have last bit zero.
+    # (The second bit is reserved as tag to allow extensions of this scheme.)
+    # Using immediates as pointers and dereferencing them gives address errors.
     nom = nlGetNumerator(n, _ring.cf)
     mpz_init(nom_z)
 
-    if (SR_HDL(nom) & SR_INT): mpz_set_si(nom_z, SR_TO_INT(nom))
-    else: mpz_set(nom_z,nom.z)
+    if SR_HDL(nom) & SR_INT:
+        mpz_set_si(nom_z, SR_TO_INT(nom))
+    else:
+        mpz_set(nom_z,nom.z)
 
     mpq_set_num(_z,nom_z)
     nlDelete(&nom,_ring.cf)
@@ -114,8 +116,10 @@ cdef Rational si2sa_QQ(number *n, number **nn, ring *_ring):
     denom = nlGetDenom(n, _ring.cf)
     mpz_init(denom_z)
 
-    if (SR_HDL(denom) & SR_INT): mpz_set_si(denom_z, SR_TO_INT(denom))
-    else: mpz_set(denom_z,denom.z)
+    if SR_HDL(denom) & SR_INT:
+        mpz_set_si(denom_z, SR_TO_INT(denom))
+    else:
+        mpz_set(denom_z,denom.z)
 
     mpq_set_den(_z, denom_z)
     nlDelete(&denom,_ring.cf)