Aligned documentation to columns 80 and other minor modifications

src/sage/graphs/graph.py

@@ -4127,26 +4127,29 @@ def tutte_symmetric_function(self, R=None, t=None):
         r"""
         Return the Tutte symmetric function of ``self``.
 
-        Let `G` be a graph. The Tutte symmetric function `XB_G` of the graph `G` was introduced in [Sta1998]_. We present
-        the equivalent definition given in [CS2022]_.
+        Let `G` be a graph. The Tutte symmetric function `XB_G` of the graph
+        `G` was introduced in [Sta1998]_. We present the equivalent definition
+        given in [CS2022]_.
 
         .. MATH::
 
             XB_G = \sum_{\pi \vdash V} (1+t)^{e(\pi)} \tilde{m}_{\lambda(\pi)},
 
-        where the sum ranges over all set-partitions `\pi` of the vertex set `V`, `\lambda(pi)` is the
-        partition determined by the sizes of the blocks of `\pi`, and `e(pi)` is the number of edges whose endpoints
-        lie in the same block of `\pi`. In particular, the coefficients of `XB_G`
-        when expanded in terms of augmented monomial symmetric functions are polynomials in `t` with
-        non-negative integer coefficients.
+        where the sum ranges over all set-partitions `\pi` of the vertex set
+        `V`, `\lambda(pi)` is the partition determined by the sizes of the
+        blocks of `\pi`, and `e(pi)` is the number of edges whose endpoints
+        lie in the same block of `\pi`. In particular, the coefficients of
+        `XB_G` when expanded in terms of augmented monomial symmetric functions
+        are polynomials in `t` with non-negative integer coefficients.
 
-        For an integer partition `\lambda = 1^{r_1}2^{r_2}\cdots` expressed in the exponential notation, the augmented monomial symmetric function is defined as
+        For an integer partition `\lambda = 1^{r_1}2^{r_2}\cdots` expressed in
+        the exponential notation, the augmented monomial symmetric function
+        is defined as
 
         .. MATH::
 
             \tilde{m}_{\lambda} = \(\prod_{i} r_i!\) m_{\lambda}.
 
-
         INPUT:
 
         - ``R`` -- (optional) the base ring for the symmetric functions;
@@ -4160,9 +4163,12 @@ def tutte_symmetric_function(self, R=None, t=None):
             sage: p = SymmetricFunctions(ZZ).p()                                        # needs sage.combinat sage.modules
             sage: G = Graph([[1,2],[2,3],[3,4],[4,1],[1,3]])
             sage: XB_G = G.tutte_symmetric_function(); XB_G                             # needs sage.combinat sage.modules
-            24*m[1, 1, 1, 1] + (10*t+12)*m[2, 1, 1] + (4*t^2+10*t+6)*m[2, 2] + (2*t^3+8*t^2+10*t+4)*m[3, 1] + (t^5+5*t^4+10*t^3+10*t^2+5*t+1)*m[4]
+            24*m[1, 1, 1, 1] + (10*t+12)*m[2, 1, 1] + (4*t^2+10*t+6)*m[2, 2]
+            + (2*t^3+8*t^2+10*t+4)*m[3, 1]
+            + (t^5+5*t^4+10*t^3+10*t^2+5*t+1)*m[4]
             sage: p(XB_G)                                                               # needs sage.combinat sage.modules
-            p[1, 1, 1, 1] + 5*t*p[2, 1, 1] + 2*t^2*p[2, 2] + (2*t^3+8*t^2)*p[3, 1] + (t^5+5*t^4+8*t^3)*p[4]
+            p[1, 1, 1, 1] + 5*t*p[2, 1, 1] + 2*t^2*p[2, 2]
+            + (2*t^3+8*t^2)*p[3, 1] + (t^5+5*t^4+8*t^3)*p[4]
 
         Graphs are allowed to have multiedges and loops::
 
@@ -4171,13 +4177,16 @@ def tutte_symmetric_function(self, R=None, t=None):
             6*m[1, 1, 1] + (t^2+3*t+3)*m[2, 1] + (t^3+3*t^2+3*t+1)*m[3]
 
 
-        We check that at `t = -1`, we recover the usual chromatic symmetric function::
+        We check that at `t = -1`, we recover the usual chromatic symmetric
+        function::
 
             sage: G = Graph([[1,2],[1,2],[2,3],[3,4],[4,5]], multiedges=True)
             sage: XB_G = G.tutte_symmetric_function(t=-1); XB_G                         # needs sage.combinat sage.modules
-            120*m[1, 1, 1, 1, 1] + 36*m[2, 1, 1, 1] + 12*m[2, 2, 1] + 2*m[3, 1, 1] + m[3, 2]
+            120*m[1, 1, 1, 1, 1] + 36*m[2, 1, 1, 1] + 12*m[2, 2, 1]
+            + 2*m[3, 1, 1] + m[3, 2]
             sage: X_G = G.chromatic_symmetric_function(); X_G                           # needs sage.combinat sage.modules
-            p[1, 1, 1, 1, 1] - 4*p[2, 1, 1, 1] + 3*p[2, 2, 1] + 3*p[3, 1, 1] - 2*p[3, 2] - 2*p[4, 1] + p[5]
+            p[1, 1, 1, 1, 1] - 4*p[2, 1, 1, 1] + 3*p[2, 2, 1] + 3*p[3, 1, 1]
+            - 2*p[3, 2] - 2*p[4, 1] + p[5]
             sage: XB_G == X_G                                                           # needs sage.combinat sage.modules
             True
 
@@ -4195,8 +4204,7 @@ def tutte_symmetric_function(self, R=None, t=None):
         m = SymmetricFunctions(R).m()
         ret = m.zero()
         V = self.vertices()
-        E = list(self.edges(labels=False))
-        M = Counter(E)
+        M = Counter(list(self.edges(labels=False)))
         fact = [factorial(i) for i in range(len(V)+1)]
 
         def mono(pi):