Completed transition of the symbol '|' from fraction to operator binary or. New fraction symbol is ':'.

Also, fixed and improved some parsing sections concerning collection indeces and ranges

fraction-type.go

@@ -50,9 +50,9 @@ func makeGeneratingFraction(s string) (f *FractionType, err error) {
 	} else if s[0] == '+' {
 		s = s[1:]
 	}
-//	if strings.HasSuffix(s, "()") {
-//		s = s[0 : len(s)-2]
-//	}
+	//	if strings.HasSuffix(s, "()") {
+	//		s = s[0 : len(s)-2]
+	//	}
 	s = strings.TrimSuffix(s, "()")
 	parts = strings.SplitN(s, ".", 2)
 	if num, err = strconv.ParseInt(parts[0], 10, 64); err != nil {
@@ -124,7 +124,7 @@ func (f *FractionType) String() string {
 func (f *FractionType) ToString(opt FmtOpt) string {
 	var sb strings.Builder
 	if opt&MultiLine == 0 {
-		sb.WriteString(fmt.Sprintf("%d|%d", f.num, f.den))
+		sb.WriteString(fmt.Sprintf("%d:%d", f.num, f.den))
 	} else {
 		var s, num string
 		if f.num < 0 && opt&TTY == 0 {