chapter06 Remove Assignments to Parameters #2

Explain Remove Assignments to Parameters refactor
Use a temporary variable instead

Author: jiwhunkim

chapter06/remove_assignments_to_parameters.rb

@@ -1,7 +1,8 @@
 class RemoveAssignmentsToParameters
   def discount(input_val, quantity, year_to_date)
+    result = input_val
     if input_val > 50
-      input_val -= 2
+      result -= 2
     end
   end
 end