some simplifications suggested by ruff

spherogram_src/codecs/DT.py

@@ -293,9 +293,8 @@ def marked_arc(self, vertex):
                     raise ValueError('Marked graph has a dead end at %s.' % V)
                 if len(edges) > 1:
                     break
-                else:
-                    vertices.add(V)
-                    edge = edges.pop()
+                vertices.add(V)
+                edge = edges.pop()
         left_path.reverse()
         return left_path + right_path
 
@@ -755,10 +754,9 @@ def find_circle(self, first_edge):
             if vertex in seen:
                 edges.append(edge)
                 break
-            else:
-                seen.add(vertex)
-                vertices.append(vertex)
-                edges.append(edge)
+            seen.add(vertex)
+            vertices.append(vertex)
+            edges.append(edge)
         n = vertices.index(vertex)
         edges = edges[n:]
         vertices = vertices[n:]

spherogram_src/links/alexander.py

@@ -96,8 +96,7 @@ def strand_matrix_merge(A, a, b):
     A[:, i] = phi + alpha * psi / mu
     A[i, i] = gamma + alpha * delta / mu
     A = A.delete_rows([j])
-    A = A.delete_columns([j])
-    return A
+    return A.delete_columns([j])
 
 
 def test_meta_associativity():

spherogram_src/links/invariants.py

@@ -58,15 +58,14 @@ def normalize_alex_poly(p, t):
         p = p * (ti**(-min_exp))
 
     R = p.parent()
-    p = R.polynomial_ring()(p)
-    return p
+    return R.polynomial_ring()(p)
 
 
 def sage_braid_as_int_word(braid):
     """
     Convert a Sage Braid to a word.
     """
-    # Could simplify using braid.Tietze().
+    # TODO : Could simplify using braid.Tietze().
 
     G = braid.parent()
     gen_idx = {g: i + 1 for i, g in enumerate(G.gens())}
@@ -144,10 +143,10 @@ def knot_group(self):
 
         Returns a finitely presented group::
 
-           sage: K = Link('3_1')
-           sage: G = K.knot_group()
-           sage: type(G)
-           <class 'sage.groups.finitely_presented.FinitelyPresentedGroup_with_category'>
+            sage: K = Link('3_1')
+            sage: G = K.knot_group()
+            sage: type(G)
+            <class 'sage.groups.finitely_presented.FinitelyPresentedGroup_with_category'>
         """
         n = len(self.crossings)
         F = FreeGroup(n)

spherogram_src/links/links_base.py

@@ -278,10 +278,10 @@ def other(self):
         other = nonzero_entry_point if self.strand_index == 0 else 0
         return CrossingEntryPoint(self.crossing, other)
 
-    def is_under_crossing(self):
+    def is_under_crossing(self) -> bool:
         return self.strand_index == 0
 
-    def is_over_crossing(self):
+    def is_over_crossing(self) -> bool:
         return self.strand_index != 0
 
     def component(self):
@@ -290,8 +290,7 @@ def component(self):
             next = ans[-1].next()
             if next == self:
                 break
-            else:
-                ans.append(next)
+            ans.append(next)
 
         return ans
 
@@ -506,16 +505,15 @@ def __init__(self, crossings=None, braid_closure=None, check_planarity=True, bui
                                 # This is a second Strand in the same component
                                 # with the same component_idx, which is OK
                                 break
-                            elif component_perm[idx] is None:
+                            if component_perm[idx] is None:
                                 if i not in unused_comps:
                                     raise ValueError("Two Strand objects in the same component"
                                                      " have different component_idx values")
                                 component_perm[idx] = i
                                 unused_comps.remove(i)
                                 break
-                            else:
-                                raise ValueError("Two Strand objects in different components"
-                                                 " have the same component_idx values")
+                            raise ValueError("Two Strand objects in different components"
+                                             " have the same component_idx values")
                     else:
                         raise Exception()  # This should not happen
                 for i in range(len(self.link_components)):
@@ -1008,9 +1006,8 @@ def faces(self):
                 if next == cs0:
                     faces.append(face)
                     break
-                else:
-                    corners.remove(next)
-                    face.append(next)
+                corners.remove(next)
+                face.append(next)
 
         return faces
 
@@ -1338,8 +1335,7 @@ def linking_number(self):
             for i, m in enumerate(tally):
                 if m == 1:
                     n += (self.crossings)[i].sign
-        n = n / 4
-        return n
+        return n / 4  # should it be n // 4 ?
 
     def _pieces(self):
         """

spherogram_src/links/orthogonal.py

@@ -131,15 +131,14 @@ def __init__(self, graph, edge_and_vertex):
             vertex = edge(vertex)
             if self[0] == (edge, vertex):
                 break
-            else:
-                self.append((edge, vertex))
+            self.append((edge, vertex))
 
         self._add_turns()
 
     def _add_turns(self):
         self.turns = turns = []
         for i, (e0, v0) in enumerate(self):
-            (e1, v1) = self[i + 1]
+            e1, v1 = self[i + 1]
             if e0.kind == e1.kind:
                 turns.append(0)
             else:

spherogram_src/links/random_links.py

@@ -190,8 +190,7 @@ def random_link(crossings,
     # Adjust the currently random crossings to match the request
 
     if alternating:
-        link = link.alternating()
-        return link
+        return link.alternating()
 
     if consistent_twist_regions:
         twist.make_twist_regions_consistent(link)

spherogram_src/links/seifert.py

@@ -134,8 +134,8 @@ def remove_admissible_move(link):
                 reverse_type_II(link, cs1, cs2, label1, label2)
                 link._rebuild(same_components_and_orientations=True)
                 break
-            else:
-                found_move = False
+
+            found_move = False
     return found_move
 
 
@@ -149,7 +149,7 @@ def isotope_to_braid(link):
         pass
 
 
-def is_chain(tree):
+def is_chain(tree) -> bool:
     tails = [e[0] for e in tree]
     heads = [e[1] for e in tree]
     return len(set(tails)) == len(tails) and len(set(heads)) == len(heads)

spherogram_src/links/simplify.py

@@ -76,20 +76,20 @@ def reidemeister_I_and_II(link, A):
                 eliminated, changed = reidemeister_I(link, B)
                 if eliminated:
                     break
-                else:
-                    W, w = A.adjacent[a + 2]
-                    X, x = A.adjacent[a + 3]
-                    Y, y = B.adjacent[b + 1]
-                    Z, z = B.adjacent[b + 2]
-                    eliminated = {A, B}
-                    if W != B:
-                        W[w] = Z[z]
-                        changed.update({W, Z})
-                    if X != B:
-                        X[x] = Y[y]
-                        changed.update({X, Y})
-                    remove_crossings(link, eliminated)
-                    break
+
+                W, w = A.adjacent[a + 2]
+                X, x = A.adjacent[a + 3]
+                Y, y = B.adjacent[b + 1]
+                Z, z = B.adjacent[b + 2]
+                eliminated = {A, B}
+                if W != B:
+                    W[w] = Z[z]
+                    changed.update({W, Z})
+                if X != B:
+                    X[x] = Y[y]
+                    changed.update({X, Y})
+                remove_crossings(link, eliminated)
+                break
 
     return eliminated, changed
 
@@ -276,10 +276,9 @@ def dual_graph_as_nx(link):
             if next == face[0]:
                 faces.append(Face(face, count))
                 break
-            else:
-                to_face_index[next] = count
-                corners.remove(next)
-                face.append(next)
+            to_face_index[next] = count
+            corners.remove(next)
+            face.append(next)
 
     G = nx.Graph()
     to_face = {edge: faces[f] for edge, f in to_face_index.items()}