Update Basic Types.md

Author: DanielRosenwasser

pages/Basic Types.md

@@ -206,7 +206,7 @@ That means you can assign `null` and `undefined` to something like `number`.
 
 However, when using the `--strictNullChecks` flag, `null` and `undefined` are only assignable to `void` and their respective types.
 This helps avoid *many* common errors.
-In cases where you wanted to pass in either a `string` or `null` or `undefined`, you can use the union type `string | null | undefined`.
+In cases where you want to pass in either a `string` or `null` or `undefined`, you can use the union type `string | null | undefined`.
 Once again, more on union types later on.
 
 > As a note: we encourage the use of `--strictNullChecks` when possible, but for the purposes of this handbook, we will assume it is turned off.