Simple Calculator to calculate length of days in future.
Takes input of future year, and implements functions time_to_seconds and seconds_to_str.
time_to_seconds: takes input of three values represneting a length of time in terms of number of hours, minutes, and seconds, and returns total numbes of seconds.
seconds_to_str: takes input number of seconds and returns a string representing hours, minutes, ands econds equivalent to the input length of time.