sagemathgh-38977: minor details in some pyx files in sets

    
just fxing a few suggestions of pycodestyle there

### 📝 Checklist

- [x] The title is concise and informative.
- [x] The description explains in detail what this PR is about.
- [ ] I have linked a relevant issue or discussion.
- [ ] I have created tests covering the changes.
- [ ] I have updated the documentation and checked the documentation
preview.
    
URL: sagemath#38977
Reported by: Frédéric Chapoton
Reviewer(s): David Coudert

src/sage/sets/family.pyx

@@ -337,7 +337,10 @@ def Family(indices, function=None, hidden_keys=[], hidden_function=None, lazy=Fa
 
         sage: f = Family(list(range(1,27)), lambda i: chr(i+96))
         sage: f
-            Finite family {1: 'a', 2: 'b', 3: 'c', 4: 'd', 5: 'e', 6: 'f', 7: 'g', 8: 'h', 9: 'i', 10: 'j', 11: 'k', 12: 'l', 13: 'm', 14: 'n', 15: 'o', 16: 'p', 17: 'q', 18: 'r', 19: 's', 20: 't', 21: 'u', 22: 'v', 23: 'w', 24: 'x', 25: 'y', 26: 'z'}
+        Finite family {1: 'a', 2: 'b', 3: 'c', 4: 'd', 5: 'e', 6: 'f', 7: 'g',
+        8: 'h', 9: 'i', 10: 'j', 11: 'k', 12: 'l', 13: 'm', 14: 'n', 15: 'o',
+        16: 'p', 17: 'q', 18: 'r', 19: 's', 20: 't', 21: 'u', 22: 'v', 23: 'w',
+        24: 'x', 25: 'y', 26: 'z'}
         sage: f[2]
         'b'
 

src/sage/sets/finite_set_map_cy.pyx

@@ -621,11 +621,10 @@ cdef class FiniteSetEndoMap_N(FiniteSetMap_MN):
             sage: F([1, 0, 2]) * F([2, 1, 0])
             [1, 2, 0]
         """
-        assert(self._parent is other._parent), "Parent mismatch"
+        assert (self._parent is other._parent), "Parent mismatch"
         if self._parent._action == "right":
             return self._compose_internal_(other, self._parent)
-        else:
-            return other._compose_internal_(self, self._parent)
+        return other._compose_internal_(self, self._parent)
 
     def __pow__(self, n, dummy):
         """
@@ -679,11 +678,10 @@ cdef class FiniteSetEndoMap_Set(FiniteSetMap_Set):
             sage: g * f
             map: a -> c, b -> c, c -> c
         """
-        assert(self._parent is other._parent), "Parent mismatch"
+        assert (self._parent is other._parent), "Parent mismatch"
         if self._parent._action == "right":
             return self._compose_internal_(other, self._parent)
-        else:
-            return other._compose_internal_(self, self._parent)
+        return other._compose_internal_(self, self._parent)
 
     def __pow__(self, n, dummy):
         """

src/sage/sets/pythonclass.pyx

@@ -3,15 +3,15 @@
 Set of all objects of a given Python class
 """
 
-#*****************************************************************************
+# ****************************************************************************
 #       Copyright (C) 2018 Jeroen Demeyer <J.Demeyer@UGent.be>
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
 # the Free Software Foundation, either version 2 of the License, or
 # (at your option) any later version.
-#                  http://www.gnu.org/licenses/
-#*****************************************************************************
+#                  https://www.gnu.org/licenses/
+# ****************************************************************************
 
 from cpython.object cimport Py_EQ, Py_NE
 from sage.structure.richcmp cimport rich_to_bool

src/sage/sets/recursively_enumerated_set.pyx

@@ -286,8 +286,9 @@ from collections import deque
 
 
 def RecursivelyEnumeratedSet(seeds, successors, structure=None,
-            enumeration=None, max_depth=float("inf"), post_process=None,
-            facade=None, category=None):
+                             enumeration=None, max_depth=float("inf"),
+                             post_process=None,
+                             facade=None, category=None):
     r"""
     Return a recursively enumerated set.
 
@@ -470,7 +471,7 @@ cdef class RecursivelyEnumeratedSet_generic(Parent):
             A recursively enumerated set (breadth first search)
         """
         assert enumeration in ['naive', 'depth', 'breadth'], \
-                    "unknown enumeration(={})".format(enumeration)
+            "unknown enumeration(={})".format(enumeration)
 
         self._seeds = seeds
         self.successors = successors
@@ -480,7 +481,8 @@ cdef class RecursivelyEnumeratedSet_generic(Parent):
         if post_process is not None:
             self.post_process = post_process
         self._graded_component = None
-        Parent.__init__(self, facade=facade, category=EnumeratedSets().or_subcategory(category))
+        Parent.__init__(self, facade=facade,
+                        category=EnumeratedSets().or_subcategory(category))
 
     def __reduce__(self):
         r"""
@@ -1532,10 +1534,7 @@ def search_forest_iterator(roots, children, algorithm='depth'):
     # (you ask the children for the last node you met). Setting
     # position on 0 results in a breadth search (enumerate all the
     # descendants of a node before going on to the next father)
-    if algorithm == 'depth':
-        position = -1
-    else:
-        position = 0
+    position = -1 if algorithm == 'depth' else 0
 
     # Invariant:
     #  - for breadth first search: stack[i] contains an iterator over the nodes
@@ -1555,7 +1554,7 @@ def search_forest_iterator(roots, children, algorithm='depth'):
             continue
 
         yield node
-        stack.append( iter(children(node)) )
+        stack.append(iter(children(node)))
 
 
 class RecursivelyEnumeratedSet_forest(Parent):
@@ -1742,8 +1741,8 @@ class RecursivelyEnumeratedSet_forest(Parent):
             sage: loads(dumps(S))
             An enumerated set with a forest structure
     """
-    def __init__(self, roots = None, children = None, post_process = None,
-                 algorithm = 'depth', facade = None, category=None):
+    def __init__(self, roots=None, children=None, post_process=None,
+                 algorithm='depth', facade=None, category=None):
         r"""
         TESTS::
 
@@ -1759,7 +1758,8 @@ class RecursivelyEnumeratedSet_forest(Parent):
         if post_process is not None:
             self.post_process = post_process
         self._algorithm = algorithm
-        Parent.__init__(self, facade = facade, category = EnumeratedSets().or_subcategory(category))
+        Parent.__init__(self, facade=facade,
+                        category=EnumeratedSets().or_subcategory(category))
 
     __len__ = None
 
@@ -1833,7 +1833,7 @@ class RecursivelyEnumeratedSet_forest(Parent):
         """
         iter = search_forest_iterator(self.roots(),
                                       self.children,
-                                      algorithm = self._algorithm)
+                                      algorithm=self._algorithm)
         if hasattr(self, "post_process"):
             iter = _imap_and_filter_none(self.post_process, iter)
         return iter
@@ -2016,7 +2016,7 @@ class RecursivelyEnumeratedSet_forest(Parent):
         """
         stack = [iter(self.roots())]
         while stack:
-            position = randint(0,len(stack)-1)
+            position = randint(0, len(stack) - 1)
             try:
                 node = next(stack[position])
             except StopIteration:
@@ -2025,12 +2025,12 @@ class RecursivelyEnumeratedSet_forest(Parent):
 
             if node == elt:
                 return True
-            stack.append( iter(self.children(node)) )
+            stack.append(iter(self.children(node)))
         return False
 
-    def map_reduce(self, map_function = None,
-                   reduce_function = None,
-                   reduce_init = None):
+    def map_reduce(self, map_function=None,
+                   reduce_function=None,
+                   reduce_init=None):
         r"""
         Apply a Map/Reduce algorithm on ``self``.
 
@@ -2084,7 +2084,7 @@ class RecursivelyEnumeratedSet_forest(Parent):
         """
         import sage.parallel.map_reduce
         return sage.parallel.map_reduce.RESetMapReduce(
-            forest = self,
-            map_function = map_function,
-            reduce_function = reduce_function,
-            reduce_init = reduce_init).run()
+            forest=self,
+            map_function=map_function,
+            reduce_function=reduce_function,
+            reduce_init=reduce_init).run()