Made 'FindString' a method of 'Reg'

regex/matching.go

@@ -142,7 +142,7 @@ func pruneIndices(indices []Match) []Match {
 // the regex, in the given string. The return value will be an empty string in two situations:
 //  1. No match was found
 //  2. The match was an empty string
-func FindString(regex Reg, str string) string {
+func (regex Reg) FindString(str string) string {
 	match, err := FindNthMatch(regex, str, 1)
 	if err != nil {
 		return ""