Merge pull request #2990 from tylersernett/patch-2

Update part4a.md: Fix typo

Author: mluukkai

src/content/4/en/part4a.md

@@ -771,7 +771,7 @@ Write the tests for this exercise inside of a new <i>describe</i> block. Do the
 
 #### 4.6*: helper functions and unit tests, step4
 
-This and the next exercise are a little bit more challenging. Finishing these two exercises is not required in to advance in the course material, so it may be a good idea to return to these once you're done going through the material for this part in its entirety.
+This and the next exercise are a little bit more challenging. Finishing these two exercises is not required to advance in the course material, so it may be a good idea to return to these once you're done going through the material for this part in its entirety.
 
 Finishing this exercise can be done without the use of additional libraries. However, this exercise is a great opportunity to learn how to use the [Lodash](https://lodash.com/) library.