some fixes for pycodestyle linter

[fchapoton]

Also

• fix one lgtm suggestion
• remove some #py2 / #py3 doctest tags

CC: @tscrim @slel @kliem

Component: refactoring

Author: Frédéric Chapoton

Branch/Commit: e79e59e

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/32279

[fchapoton]

New commits:

5f756e0	fix pycodestyle warnings (polishing)
b3dc3f0	one lgtm-suggested fix in pq_trees.py
e79e59e	some py2 / py3 doctest tagging removal

[fchapoton]

Commit: e79e59e

[fchapoton]

Branch: u/chapoton/32279

[fchapoton]

comment:2

bot is morally green, and one linter is green (out of 3)

about pyflakes warnings from patchbot : one is harmless, the other is serious but should be handled elsewhere

please review

[tscrim]

comment:3

That one in categories/finite_dimensional_algebras_with_basis.py is bad and needs to be fixed. It can be left to another ticket.

[tscrim]

Reviewer: Travis Scrimshaw

[tscrim]

comment:4

Replying to @tscrim:

That one in categories/finite_dimensional_algebras_with_basis.py is bad and needs to be fixed. It can be left to another ticket.

This is now #32283.

[jhpalmieri]

comment:6

Do you know if this one has been fixed anywhere?

diff --git a/src/sage/combinat/posets/poset_examples.py b/src/sage/combinat/posets/poset_examples.py
index 67d9949db1..7913c50f7d 100644
--- a/src/sage/combinat/posets/poset_examples.py
+++ b/src/sage/combinat/posets/poset_examples.py
@@ -155,7 +155,7 @@ class Posets(metaclass=ClasscallMetaclass):
 
     @staticmethod
     def BooleanLattice(n, facade=None, use_subsets=False):
-        """
+        r"""
         Return the Boolean lattice containing `2^n` elements.
 
         - ``n`` -- integer; number of elements will be `2^n`

The code as is produces

[combinat ] <unknown>:158: DeprecationWarning: invalid escape sequence \{

[vbraun]

Changed branch from u/chapoton/32279 to e79e59e