lib/axlsx/workbook/worksheet/rich_text.rb in caxlsx-3.4.1 vs lib/axlsx/workbook/worksheet/rich_text.rb in caxlsx-4.0.0

@@ -1,5 +1,7 @@
+# frozen_string_literal: true
+
 module Axlsx
   # A simple, self serializing class for storing TextRuns
   class RichText < SimpleTypedList
     # creates a new RichText collection
     # @param [String] text -optional The text to use in creating the first RichTextRun
@@ -43,10 +45,10 @@
     end
 
     # renders the RichTextRuns in this collection
     # @param [String] str
     # @return [String]
-    def to_xml_string(str = '')
+    def to_xml_string(str = +'')
       each { |run| run.to_xml_string(str) }
       str
     end
   end
 end