Reviewer changes: refactored some of the divided difference code, doc changes, orther misc changes.

Author: tscrim

src/doc/en/reference/combinat/module_list.rst

@@ -145,6 +145,7 @@ Comprehensive Module List
     sage/combinat/k_regular_sequence
     sage/combinat/k_tableau
     sage/combinat/kazhdan_lusztig
+    sage/combinat/key_polynomial
     sage/combinat/knutson_tao_puzzles
     sage/combinat/matrices/all
     sage/combinat/matrices/dancing_links

src/sage/combinat/algebraic_combinatorics.py

@@ -41,6 +41,7 @@
 - :class:`~sage.combinat.symmetric_group_representations.SymmetricGroupRepresentation`
 - :ref:`sage.combinat.yang_baxter_graph`
 - :ref:`sage.combinat.hall_polynomial`
+- :ref:`sage.combinat.key_polynomial`
 
 Operads and their algebras
 --------------------------

src/sage/combinat/all.py

@@ -87,6 +87,7 @@
 from .debruijn_sequence import DeBruijnSequences
 
 from .schubert_polynomial import SchubertPolynomialRing
+lazy_import('sage.combinat.key_polynomial', 'KeyPolynomialBasis', as_='KeyPolynomials')
 from .symmetric_group_algebra import SymmetricGroupAlgebra, HeckeAlgebraSymmetricGroupT
 from .symmetric_group_representations import SymmetricGroupRepresentation, SymmetricGroupRepresentations
 from .yang_baxter_graph import YangBaxterGraph

src/sage/combinat/integer_vector.py

@@ -494,6 +494,7 @@ def trim(self):
             [4, 3, 3]
             sage: IV([0,0,0]).trim()
             []
+
             sage: IV = IntegerVectors(k=4)
             sage: v = IV([4,3,2,0]).trim(); v
             [4, 3, 2]
@@ -508,7 +509,6 @@ def trim(self):
             v = v[:-1]
         return P.element_class(P, v, check=False)
 
-
 class IntegerVectors(Parent, metaclass=ClasscallMetaclass):
     """
     The class of (non-negative) integer vectors.