The purpose of a meter is to signal proportional completion of a task and to be able to trigger another job which is waiting this proportional completion. Let us say that task "model" creates a hundred files, and there are ten other tasks to process these files. Task "t0" processes files 0-9, task "t1" files 10-19 and so on. The python API would look something like: 
  suite = Suite("x")
  f = suite.add_family("f") 
  task_model = f.add_task("model")
  task_model.add_meter("file",0,100,100)
  for i in range(0,9):
  file = i*10 + 10
  t = f.add_task("t" + str)
  t.add_trigger("model:file ge " + str(file))