Calculates at what time I have to leave the office given an start time and the pending time.

hours.py

#!/usr/bin/env python3

import sys

time_spaces = ['AM', 'PM']


def main(argv):
    try:
        start = argv[0]
        time_space = argv[1]
        pending = argv[2]
    except:
        print('usage: hours <start_hour> <AM|PM> <pending_time>\n')
        sys.exit(2)

    try:
        start_h, start_m = map(int, start.split(':'))
        pending_h, pending_m = map(int, pending.split(':'))
    except:
        print('format for dates is: HH:MM\n')
        sys.exit(2)

    try:
        time_spaces.index(time_space)
    except:
        print('format for timespace is AM or PM\n')
        sys.exit(2)
    
    finish_h = start_h + pending_h
    finish_m = start_m + pending_m
    hours_plus, finish_m = divmod(finish_m, 60)
    finish_h += hours_plus
    hours_plus, finish_h = divmod(finish_h, 12)
    if finish_h + finish_m == 0:
        finish_h = 12
    try:
        finish_time_space = time_spaces[time_spaces.index(time_space) + hours_plus]
    except:
        finish_time_space = time_spaces[0]
    print(f'{finish_h:02}:{finish_m:02} {finish_time_space}\n')


if __name__ == "__main__":
    main(sys.argv[1:])

To install:
Copy to /usr/local/bin without the extension.
Should look like this: /usr/local/bin/hours
To add execution permissions: chmod +x /usr/local/bin/hours
Run directly in your terminal by typing: hours