Incr_map_collate.Instrumentationtype t = {key_to_rank : Incr_map.Instrumentation.t;Invoked when converting the key range to a rank range
*)subrange_by_rank : Incr_map.Instrumentation.t;Invoked when subrange_by_rank is computed, to compute the reduced range
filter : Incr_map.Instrumentation.t;Invoked when the filter is computed
*)fold : Incr_map.Instrumentation.t;Invoked at the end when folding back into the resulting data structure
*)sort : Incr_map.Instrumentation.t;Invoked when the dataset is being sorted
*)}Gives an instrumentation hook at various points into the phases of Incr_map_collate.