t2h.py

#!/usr/bin/env python3

def duration_to_hours(duration):
    if duration.isdigit():
        # Default to minutes
        return float(duration) / 60.0

    def get_unit(unit):
        nonlocal duration
        if unit in duration:
            if duration[-1] == unit:
                result = float(duration[:-1])
            else:
                result, duration = duration.split(unit)
                result = float(result)
        else:
            result = 0.0
        return result

    hours = get_unit('h')
    minutes = get_unit('m')
    seconds = get_unit('s')
    
    hours = hours + minutes/60.0 + seconds/60.0/60.0
    
    return hours


if __name__ == '__main__':
    import sys
    print(duration_to_hours(sys.argv[1]))