copy/copy.go
func isTTY(w io.Writer) bool {
	if f, ok := w.(*os.File); ok {
		return terminal.IsTerminal(int(f.Fd()))
	}
	return false
}
func isTTY(w io.Writer) bool {
	if f, ok := w.(*os.File); ok {
		return terminal.IsTerminal(int(f.Fd()))
	}
	return false
}
func isTTY ( w io . Writer ) bool { if f , ok := w . ( * os . File ) ; ok { return terminal . IsTerminal ( int ( f . Fd ( ) ) ) } return false }
// isTTY returns true if the io.Writer is a file and a tty.
isTTY returns true if the io . Writer is a file and a tty .