of_linear start interval count will return a histogram type with count buckets with values starting at start and interval apart: (start, start+interval, start + (2 * interval), ... start + ((count-1) * interval), infinity). count does not include the infinity bucket.

of_exponential start factor count will return a histogram type with count buckets with values starting at start and every next item previous*factor. count does not include the infinity bucket.

of_list [0.5; 1.] will return a histogram with buckets 0.5;1.;infinity.