Remove extra parentheses in output formatting tutorial (GH-8350)

The parentheses were incorrect.

Doc/tutorial/inputoutput.rst

@@ -41,8 +41,8 @@ printing space-separated values. There are several ways to format output.
   ::
 
      >>> yes_votes = 42_572_654 ; no_votes = 43_132_495
-     >>> percentage = (yes_votes/(yes_votes+no_votes)
-     >>> '{:-9} YES votes  {:2.2%}'.format(yes_votes, percentage))
+     >>> percentage = yes_votes/(yes_votes+no_votes)
+     >>> '{:-9} YES votes  {:2.2%}'.format(yes_votes, percentage)
      ' 42572654 YES votes  49.67%'
 
 * Finally, you can do all the string handling yourself by using string slicing and