Merge pull request #1882 from kimhongji/patch-1

Update polymorphic-methods.md

Author: Philippus

_tour/polymorphic-methods.md

@@ -27,7 +27,7 @@ println(listOfDuplicates[Int](3, 4))  // List(3, 3, 3, 3)
 println(listOfDuplicates("La", 8))  // List(La, La, La, La, La, La, La, La)
 ```
 
-The method `listOfDuplicates` takes a type parameter `A` and value parameters `x` and `length`. Value `x` is of type `A`. If `length < 1` we return an empty list. Otherwise we prepend `x` to the the list of duplicates returned by the recursive call. (Note that `::` means prepend an element on the left to a list on the right.)
+The method `listOfDuplicates` takes a type parameter `A` and value parameters `x` and `length`. Value `x` is of type `A`. If `length < 1` we return an empty list. Otherwise we prepend `x` to the list of duplicates returned by the recursive call. (Note that `::` means prepend an element on the left to a list on the right.)
 
 In first example call, we explicitly provide the type parameter by writing `[Int]`. Therefore the first argument must be an `Int` and the return type will be `List[Int]`.