func NumberLines() Filter {
	return FilterFunc(func(arg Arg) error {
		line := 1
		for s := range arg.In {
			arg.Out <- fmt.Sprintf("%5d %s", line, s)
			line++
		}
		return nil
	})
}
func NumberLines() Filter {
	return FilterFunc(func(arg Arg) error {
		line := 1
		for s := range arg.In {
			arg.Out <- fmt.Sprintf("%5d %s", line, s)
			line++
		}
		return nil
	})
}
func NumberLines ( ) Filter { return FilterFunc ( func ( arg Arg ) error { line := 1 for s := range arg . In { arg . Out <- fmt . Sprintf ( " " , line , s ) line ++ } return nil } ) }
// NumberLines prefixes its item with its index in the input sequence
// (starting at 1) followed by a space.
NumberLines prefixes its item with its index in the input sequence ( starting at 1 ) followed by a space .