--- a/qiime2/qiime_diversity_beta-rarefaction.xml	Wed Jul 17 03:26:16 2019 -0400
+++ b/qiime2/qiime_diversity_beta-rarefaction.xml	Thu Jul 18 12:19:15 2019 -0400
@@ -28,6 +28,7 @@
  --p-color-scheme=$pcolorscheme
 #end if
 
+#if $input_files_mmetadatafile:
 #def list_dict_to_string(list_dict):
 #set $file_list = list_dict[0]['additional_input'].__getattr__('file_name')
 #for d in list_dict[1:]:
@@ -35,9 +36,8 @@
 #end for
 #return $file_list
 #end def
-
 --m-metadata-file=$list_dict_to_string($input_files_mmetadatafile)
-
+#end if
 
 --o-visualization=ovisualization
 ;