func SubstrF(index, n int) func(string) string {
	return func(s string) string {
		return Substr(s, index, n)
	}
}
func SubstrF(index, n int) func(string) string {
	return func(s string) string {
		return Substr(s, index, n)
	}
}
func SubstrF ( index , n int ) func ( string ) string { return func ( s string ) string { return Substr ( s , index , n ) } }
// SubstrF is the filter form of Substr.
SubstrF is the filter form of Substr .