return nil from import (#1177)

Hi,

can you please review patch to have `import` to return `nil`. It
addresses #1174.

I haven't included a test for this case, nor mentioned it in the
docstring, implying the return value is unspecified. I'm not sure this
is something we want to fix at the API level (although I did request it
as an aesthetic addition).

---------

Co-authored-by: ikappaki <[email protected]>

Author: ikappaki

CHANGELOG.md

@@ -5,6 +5,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Changed
+ * `import` now returns nil instead of the last module's string representation (#1174)
 
 ## [v0.3.5]
 ### Changed

src/basilisp/core.lpy

@@ -4936,7 +4936,8 @@
   ;; to the new ns, the global python namespace can still refer to the
   ;; old python global ns where the import would have been evaluated
   ;; otherwise.
-  (let [form `(import* ~@modules)]
+  (let [form `(do (import* ~@modules)
+                  nil)]
     `(eval '~form  *ns*)))
 
 (defn ^:private rewrite-clojure-libspec