Write a function total_beats(durations, min_beat) that receives a list of integer beat lengths of musical notes and an integer min_beat. Return the sum of all beats that are at least min_beat. If no beats meet the criterion, return 0.
Examples
total_beats([1, 3, 5, 2], 3) # returns 8 (3+5)
total_beats([], 4) # returns 0