class_docstr: similar to step but it allows non uniform steps defined by stepSizes
  
  
  :param step_size: the series of step sizes used for lr decay
  :param gamma: coefficient of decay
  
  
  >>> step = MultiStep([2, 5], 0.3)
  creating: createMultiStep
code: def __init__(self, step_sizes, gamma):
      from bigdl.optim.optimizer import MultiStep as BMultiStep
  
      self.scheduler = BMultiStep(step_sizes, gamma)
  
imports: from abc import ABC, abstractmethod
label_desc: Use image node_id 1 to create a new MultiStep object from inherited base classes: Scheduler with example: obj = MultiStep(step_sizes, gamma)