Improve the below golang function. also provide some simple unittest so I can test the refactored function
func ParseTimeStringToTime(RequestID, TimeString string) time.Time {
	var date1 time.Time
	var err error
	loc, _ := time.LoadLocation("Asia/Kolkata")
	if TimeString != "" {
		date1, err = time.ParseInLocation("2006-01-02T15:04:05", TimeString, loc)
		if err != nil {
			date1, err = time.ParseInLocation("02/01/2006", TimeString, loc)
			if err != nil {
				date1, err = time.ParseInLocation("2006-01-02T15:04:05.000000", TimeString, loc)
				if err != nil {
					date1, err = time.ParseInLocation("02/1/2006", TimeString, loc)
					if err != nil {
						date1, err = time.ParseInLocation("2/01/2006", TimeString, loc)
						if err != nil {
							date1, err = time.ParseInLocation("2/1/2006", TimeString, loc)
							if err != nil {
								glog.Error(RequestID, " Error: ", err)
							}
						}
					}
				}
			}
		}
	}

	return date1
} Respond with more than 100 words.
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