sagemathgh-39477: typing and details in tableaux files
    
add `-> bool` typing to some methods in three files related to tableaux

also very minor code details

### 📝 Checklist

- [x] The title is concise and informative.
- [x] The description explains in detail what this PR is about.
    
URL: sagemath#39477
Reported by: Frédéric Chapoton
Reviewer(s): Travis Scrimshaw

Author: Release Manager

src/sage/combinat/ribbon_tableau.py

@@ -26,7 +26,8 @@
 from sage.rings.integer import Integer
 from sage.combinat.combinat import CombinatorialElement
 from sage.combinat.skew_partition import SkewPartition, SkewPartitions
-from sage.combinat.skew_tableau import SkewTableau, SkewTableaux, SemistandardSkewTableaux
+from sage.combinat.skew_tableau import (SkewTableau, SkewTableaux,
+                                        SemistandardSkewTableaux)
 from sage.combinat.tableau import Tableaux
 from sage.combinat.partition import Partition, _Partitions
 from sage.combinat.permutation import to_standard
@@ -94,7 +95,8 @@ def __classcall_private__(cls, rt=None, expr=None):
         try:
             rt = [tuple(row) for row in rt]
         except TypeError:
-            raise TypeError("each element of the ribbon tableau must be an iterable")
+            raise TypeError("each element of the ribbon tableau "
+                            "must be an iterable")
         if not all(row for row in rt):
             raise TypeError("a ribbon tableau cannot have empty rows")
         # calls the inherited __init__ method (of SkewTableau )
@@ -195,9 +197,10 @@ class RibbonTableaux(UniqueRepresentation, Parent):
 
     REFERENCES:
 
-    .. [vanLeeuwen91] Marc. A. A. van Leeuwen, *Edge sequences, ribbon tableaux,
-       and an action of affine permutations*. Europe J. Combinatorics. **20**
-       (1999). http://wwwmathlabo.univ-poitiers.fr/~maavl/pdf/edgeseqs.pdf
+    .. [vanLeeuwen91] Marc. A. A. van Leeuwen, *Edge sequences,
+       ribbon tableaux, and an action of affine permutations*.
+       Europe J. Combinatorics. **20** (1999).
+       http://wwwmathlabo.univ-poitiers.fr/~maavl/pdf/edgeseqs.pdf
     """
     @staticmethod
     def __classcall_private__(cls, shape=None, weight=None, length=None):
@@ -318,10 +321,11 @@ def __iter__(self):
             sage: RibbonTableaux([[2,2],[]],[1,1],2).list()
             [[[0, 0], [1, 2]], [[1, 0], [2, 0]]]
         """
-        for x in graph_implementation_rec(self._shape, self._weight, self._length, list_rec):
+        for x in graph_implementation_rec(self._shape, self._weight,
+                                          self._length, list_rec):
             yield self.from_expr(x)
 
-    def _repr_(self):
+    def _repr_(self) -> str:
         """
         Return a string representation of ``self``.
 
@@ -332,7 +336,7 @@ def _repr_(self):
         """
         return "Ribbon tableaux of shape %s and weight %s with %s-ribbons" % (repr(self._shape), list(self._weight), self._length)
 
-    def __contains__(self, x):
+    def __contains__(self, x) -> bool:
         """
         Note that this just checks to see if ``x`` appears in ``self``.
 
@@ -855,7 +859,7 @@ def weight(self):
             [5, 3, 1]
         """
         weights = [x.weight() for x in self]
-        m = max([len(x) for x in weights])
+        m = max(len(x) for x in weights)
         weight = [0] * m
         for w in weights:
             for i in range(len(w)):

src/sage/combinat/skew_tableau.py

@@ -620,7 +620,7 @@ def weight(self):
 
     evaluation = weight
 
-    def is_standard(self):
+    def is_standard(self) -> bool:
         """
         Return ``True`` if ``self`` is a standard skew tableau and ``False``
         otherwise.
@@ -640,7 +640,7 @@ def is_standard(self):
         w = [i for row in self for i in row if i is not None]
         return sorted(w) == list(range(1, len(w) + 1)) and self.is_semistandard()
 
-    def is_semistandard(self):
+    def is_semistandard(self) -> bool:
         """
         Return ``True`` if ``self`` is a semistandard skew tableau and
         ``False`` otherwise.
@@ -1324,7 +1324,7 @@ def shuffle(self, t2):
             corner = self.cells_containing(i)[0]
 
             # slide t2_new backwards, record i in the vacated square
-            (t2_new, (x, y)) = t2_new.slide(corner, True)
+            t2_new, (x, y) = t2_new.slide(corner, True)
             t1_new[x][y] = i
 
         t1_new = SkewTableau(t1_new)
@@ -1582,10 +1582,12 @@ def to_expr(self):
         rows.reverse()
         return [self.inner_shape(), rows]
 
-    def is_ribbon(self):
+    def is_ribbon(self) -> bool:
         r"""
         Return ``True`` if and only if the shape of ``self`` is a
-        ribbon, that is, if it has exactly one cell in each of `q`
+        ribbon.
+
+        This means that it has exactly one cell in each of `q`
         consecutive diagonals for some nonnegative integer `q`.
 
         EXAMPLES::
@@ -1824,7 +1826,7 @@ def cells_containing(self, i):
                     cell_list.append((r, c))
         return cell_list
 
-    def is_k_tableau(self, k):
+    def is_k_tableau(self, k) -> bool:
         r"""
         Check whether ``self`` is a valid skew weak `k`-tableau.
 
@@ -1857,11 +1859,9 @@ def _label_skew(list_of_cells, sk):
         sage: skew_tableau._label_skew(l, empty)
         [[1, 4], [3, 2]]
     """
-    i = 1
     skew = [list(row) for row in sk]
-    for row, column in list_of_cells:
+    for i, (row, column) in enumerate(list_of_cells, start=1):
         skew[row][column] = i
-        i += 1
     return skew
 
 

src/sage/combinat/tableau.py

@@ -1298,7 +1298,7 @@ def to_sign_matrix(self, max_entry=None):
                 raise ValueError("the entries must be nonnegative integers")
         from sage.matrix.matrix_space import MatrixSpace
         if max_entry is None:
-            max_entry = max([max(c) for c in self])
+            max_entry = max(max(c) for c in self)
         MS = MatrixSpace(ZZ, len(self[0]), max_entry)
         Tconj = self.conjugate()
         conj_len = len(Tconj)
@@ -1694,7 +1694,7 @@ def weight(self):
 
     evaluation = weight
 
-    def is_row_strict(self):
+    def is_row_strict(self) -> bool:
         """
         Return ``True`` if ``self`` is a row strict tableau and ``False``
         otherwise.
@@ -1715,7 +1715,7 @@ def is_row_strict(self):
         """
         return all(row[i] < row[i+1] for row in self for i in range(len(row)-1))
 
-    def is_row_increasing(self, weak=False):
+    def is_row_increasing(self, weak=False) -> bool:
         r"""
         Return ``True`` if the entries in each row are in increasing order,
         and ``False`` otherwise.
@@ -1741,7 +1741,7 @@ def test(a, b):
                 return a < b
         return all(test(a, b) for row in self for (a, b) in zip(row, row[1:]))
 
-    def is_column_increasing(self, weak=False):
+    def is_column_increasing(self, weak=False) -> bool:
         r"""
         Return ``True`` if the entries in each column are in increasing order,
         and ``False`` otherwise.
@@ -1770,7 +1770,7 @@ def tworow(a, b):
             return all(test(a[i], b_i) for i, b_i in enumerate(b))
         return all(tworow(self[r], self[r + 1]) for r in range(len(self) - 1))
 
-    def is_column_strict(self):
+    def is_column_strict(self) -> bool:
         """
         Return ``True`` if ``self`` is a column strict tableau and ``False``
         otherwise.
@@ -1801,7 +1801,7 @@ def tworow(a, b):
             return all(a[i] < b_i for i, b_i in enumerate(b))
         return all(tworow(self[r], self[r+1]) for r in range(len(self)-1))
 
-    def is_semistandard(self):
+    def is_semistandard(self) -> bool:
         r"""
         Return ``True`` if ``self`` is a semistandard tableau, and ``False``
         otherwise.
@@ -1824,7 +1824,7 @@ def is_semistandard(self):
         """
         return self.is_row_increasing(weak=True) and self.is_column_increasing()
 
-    def is_standard(self):
+    def is_standard(self) -> bool:
         """
         Return ``True`` if ``self`` is a standard tableau and ``False``
         otherwise.
@@ -1843,7 +1843,7 @@ def is_standard(self):
         entries = sorted(self.entries())
         return entries == list(range(1, self.size() + 1)) and self.is_row_strict() and self.is_column_strict()
 
-    def is_increasing(self):
+    def is_increasing(self) -> bool:
         """
         Return ``True`` if ``self`` is an increasing tableau and
         ``False`` otherwise.
@@ -1865,7 +1865,7 @@ def is_increasing(self):
         """
         return self.is_row_strict() and self.is_column_strict()
 
-    def is_rectangular(self):
+    def is_rectangular(self) -> bool:
         """
         Return ``True`` if the tableau ``self`` is rectangular and
         ``False`` otherwise.
@@ -2067,7 +2067,7 @@ def k_weight(self, k):
 
         return res
 
-    def is_k_tableau(self, k):
+    def is_k_tableau(self, k) -> bool:
         r"""
         Check whether ``self`` is a valid weak `k`-tableau.
 
@@ -2518,7 +2518,7 @@ def reverse_bump(self, loc):
         if not (self.is_semistandard()):
             raise ValueError("reverse bumping is only defined for semistandard tableaux")
         try:
-            (r, c) = loc
+            r, c = loc
             if (r, c) not in self.corners():
                 raise ValueError("invalid corner")
         except TypeError:
@@ -3177,7 +3177,7 @@ def add_entry(self, cell, m):
             IndexError: (2, 2) is not an addable cell of the tableau
         """
         tab = self.to_list()
-        (r, c) = cell
+        r, c = cell
         try:
             tab[r][c] = m   # will work if we are replacing an entry
         except IndexError:
@@ -3616,7 +3616,7 @@ def symmetric_group_action_on_entries(self, w):
         except Exception:
             return Tableau([[w[entry-1] for entry in row] for row in self])
 
-    def is_key_tableau(self):
+    def is_key_tableau(self) -> bool:
         r"""
         Return ``True`` if ``self`` is a key tableau or ``False`` otherwise.
 
@@ -4788,7 +4788,7 @@ def dominates(self, t):
         return all(self.restrict(m).shape().dominates(t.restrict(m).shape())
                    for m in range(1, 1 + self.size()))
 
-    def is_standard(self):
+    def is_standard(self) -> bool:
         """
         Return ``True`` since ``self`` is a standard tableau.
 

src/sage/combinat/tableau_tuple.py

@@ -823,7 +823,7 @@ def entry(self, l, r, c):
         """
         return self[l][r][c]
 
-    def is_row_strict(self):
+    def is_row_strict(self) -> bool:
         """
         Return ``True`` if the tableau ``self`` is row strict and ``False``
         otherwise.
@@ -874,7 +874,7 @@ def first_row_descent(self):
                 return (k, cell[0], cell[1])
         return None
 
-    def is_column_strict(self):
+    def is_column_strict(self) -> bool:
         """
         Return ``True`` if the tableau ``self`` is column strict and ``False``
         otherwise.
@@ -925,7 +925,7 @@ def first_column_descent(self):
                 return (k, cell[0], cell[1])
         return None
 
-    def is_standard(self):
+    def is_standard(self) -> bool:
         r"""
         Return ``True`` if the tableau ``self`` is a standard tableau and
         ``False`` otherwise.
@@ -1173,7 +1173,7 @@ def add_entry(self, cell, m):
             ...
             IndexError: (2, 1, 2) is not an addable cell of the tableau
         """
-        (k, r, c) = cell
+        k, r, c = cell
         tab = self.to_list()
 
         try:
@@ -5017,7 +5017,7 @@ def random_element(self):
         while m < mu.size():
             m += 1
             i = randint(0, len(addables) - 1)  # index for a random addable cell
-            (k, r, c) = addables[i]  # the actual cell
+            k, r, c = addables[i]  # the actual cell
             # remove the cell we just added from the list addable nodes
             addables.pop(i)
             # add m into the tableau
@@ -5336,7 +5336,7 @@ def _add_entry_fast(T, cell, m):
           6  8       12 14     2 11
                               10
     """
-    (k, r, c) = cell
+    k, r, c = cell
     tab = T.to_list()
 
     try: