Revert six.iteritems in laurent_polynomial.pyx

[jdemeyer]

Revert

commit 92699fd23f29568077c577b65a1c561b7415269a
Author: Daniel Krenn <git@danielkrenn.at>
Date:   Thu Nov 10 14:40:28 2016 +0100

    Python3-ify (iteritems)

diff --git a/src/sage/rings/polynomial/laurent_polynomial.pyx b/src/sage/rings/polynomial/laurent_polynomial.pyx
index fa61705..e6db620 100644
--- a/src/sage/rings/polynomial/laurent_polynomial.pyx
+++ b/src/sage/rings/polynomial/laurent_polynomial.pyx
@@ -10,6 +10,7 @@ Elements of Laurent polynomial rings
 #                  http://www.gnu.org/licenses/
 #*****************************************************************************
 from __future__ import print_function
+from six import iterkeys, iteritems
 
 from sage.rings.integer cimport Integer
 from sage.structure.element import is_Element, coerce_binop
@@ -2482,11 +2483,11 @@ cdef class LaurentPolynomial_mpair(LaurentPolynomial_generic):
         except ValueError:
             # call _derivative() recursively on coefficients
             return P({m: c._derivative(var)
-                      for (m, c) in self.dict().iteritems()})
+                      for (m, c) in iteritems(self.dict())})
 
         # compute formal derivative with respect to generator
         d = {}
-        for m, c in self.dict().iteritems():
+        for m, c in iteritems(self.dict()):
             if m[index] != 0:
                 new_m = [u for u in m]
                 new_m[index] += -1

Cython understands dict.iteritems() and actually optimizes it (unlike six.iteritems)

CC: @dkrenn

Component: cython

Branch/Commit: u/jdemeyer/revert_six_iteritems_in_laurent_polynomial_pyx @ 1fc5c7b

Reviewer: Jeroen Demeyer

Issue created by migration from https://trac.sagemath.org/ticket/22530

[jdemeyer]

Branch: u/jdemeyer/revert_six_iteritems_in_laurent_polynomial_pyx

[jdemeyer]

New commits:

1fc5c7b

Revert "Python3-ify (iteritems)"

[jdemeyer]

Commit: 1fc5c7b

[fchapoton]

comment:4

see #22515

[jdemeyer]

Reviewer: Jeroen Demeyer

[jdemeyer]

Changed author from Jeroen Demeyer to none