def per_participant_count

      per_participant.remap { |(k, v), h| h[k] = v.size }
    end
def per_participant_count

      per_participant.remap { |(k, v), h| h[k] = v.size }
    end
Mostly a test method. Returns a Hash were keys are participant names
 and values are integers, the count of workitems for a given participant
 name.