public function clean($collection)
    {
        $entry = $this->manifest->get($collection);

        // If the collection exists on the environment then we'll proceed with cleaning the filesystem
        // This removes any double-up production and development builds.
        if (isset($this->environment[$collection]))
        {
            $this->cleanFilesystem($this->environment[$collection], $entry);
        }

        // If the collection does not exist on the environment then we'll instrcut the manifest to
        // forget this collection.
        else
        {
            $this->manifest->forget($collection);
        }

        // Cleaning the manifest is important as it will also remove unnecessary files from the
        // filesystem if a collection has been removed.
        $this->cleanManifestFiles($collection, $entry);

        $this->manifest->save();
    }