Python pandas script

I have csv files formatted like attached. I'd like a python script to analyze column h. I'd like to identify and flag each initial group where there was at least 20 consecutive identical values and then move ahead to the next different number checking again for 20 consecutive identical values. If there are not 20 values then move to next different number and try again. If there are more than 20 consecutive identical values then stop at 20 and just move on to next different number. Lastly, sum up the flags to count how many occurrences. Print the new data frame to csv and report to terminal total number of rows processed and total number of occurrences. Please include comments so I can learn and modify the script as needed. As an example I manually added the last column first 2000 rows with proper flags.