improve docstrings a bit for new struct field
diff --git a/parser.go b/parser.go
index bfeb00c..4bc9441 100644
--- a/parser.go
+++ b/parser.go
@@ -24,6 +24,11 @@
// NamespaceDelimiter separates group namespaces and option long names
NamespaceDelimiter string
+ //UnknownOptionsHandler is a function which, if non-nil, is called
+ //when the parser encounters an option that is unmapped.
+ //It takes the option name and remaining args to be parsed, and should
+ //return the (modified, if necessary) args, and a non-nil error if the
+ //handler fails.
UnknownOptionHandler func(option string, args []string) ([]string, error)
internalError error
