Minimum requirement is bash 4.1, actually, not bash 4.0

Author: Damien Nadé

README.md

@@ -6,8 +6,8 @@ An high level argument parsing library for bash.
 The purpose is to replace the option-parsing and usage-describing
 functions commonly rewritten in all scripts.
 
-This library is implemented for bash version 4. Prior versions of
-bash will fail at interpreting that code.
+This library is implemented for GNU bash version >= 4.1. Prior
+versions of bash will fail at interpreting that code.
 
 
 ### Online documentation