Given two strings in format HH:MM:SS that represent a range of time, calculate the total number of interesting time points between them (inclusive).

Interesting points happen when the time HH:MM:SS format has at most two distinct numbers.
Note: units are always padded with left zero & hours are 0-23 format

Example:

12:21:11 is interesting
00:00:00 is interesting
09:00:09 is interesting

13:41:11 is NOT interesting

you are to implement a function that specifies the interval, and you calculate the number of interesting points

def number_of_interesting_points(start_time, end_time):
	#implement here