fix wrong merge

src/sage/rings/polynomial/multi_polynomial_element.py

@@ -37,7 +37,7 @@
     ....:  + (a0*b2 - a1*b3 + a2*b0 + a3*b1)^2 + (a0*b3 + a1*b2 - a2*b1 + a3*b0)^2)
     True
 """
-#*****************************************************************************
+# ****************************************************************************
 #
 #   Sage: Open Source Mathematical Software
 #
@@ -54,7 +54,7 @@
 #  The full text of the GPL is available at:
 #
 #                  https://www.gnu.org/licenses/
-#*****************************************************************************
+# ****************************************************************************
 
 import operator
 
@@ -74,6 +74,7 @@
 from sage.rings.rational_field import QQ
 from sage.rings.fraction_field import FractionField
 
+
 class MPolynomial_element(MPolynomial):
     r"""
     Generic multivariate polynomial.
@@ -1929,7 +1930,7 @@ def _derivative(self, var=None):
         if index == -1:
             # var is not a generator; do term-by-term differentiation recursively
             # var may be, for example, a generator of the base ring
-            d = {e: x._derivative(var))
+            d = {e: x._derivative(var)
                  for e, x in self.monomial_coefficients().items()}
             d = polydict.PolyDict(d, check=False)
             d.remove_zeros()
@@ -2495,6 +2496,7 @@ def reduce(self, I):
                 p -= plt
         return r
 
+
 ###############################################################
 # Useful for some geometry code.
 ###############################################################