A fun run puts every finisher into a time band for the results page.
times holds every finishing time, in minutes. edges is a list of at least two numbers, smallest first, that marks where the bands start and stop. Band 0 runs from edges[0] to edges[1], band 1 from edges[1] to edges[2], and so on.
A time belongs to a band when it is at least the band's first edge and less than its second edge. So a time exactly on an edge goes into the band that starts there.
Task: write band_counts(times, edges) and return how many finishers fall in each band, as a plain list in band order.
0.