code: def test_PiecewiseScheduler_with_step_num(self):
      scheduler = PiecewiseScheduler([(0, 0.1), (3, 0.2), (7, 0.3)])
  
      value = scheduler.step()
      assert value == 0.1
  
      value = scheduler.step(2)
      assert value == 0.2
  
      value = scheduler.step(4)
      assert value == 0.3
  
file_path: PARL/parl/utils/tests/scheduler_test.py
imports: import unittest
  import numpy
  from parl.utils.scheduler import *
label_desc: Use image node_id 3 for calling the TestScheduler obj's underlying member method code with example usage: obj.test_PiecewiseScheduler_with_step_num() without return types