class_docstr: Class that maintains an exponential moving average.
code: def __init__(self, momentum):
      self._numerator = 0
      self._denominator = 0
      self._momentum = momentum
  
file_path: singa/examples/model_selection/TRAILS-Database-Native-Model-Selection/internal/ml/model_selection/src/controller/sampler_rl/reinforcement_learning.py
imports: from src.controller.core.sample import Sampler
  from src.search_space.core.space import SpaceWrapper
  from src.search_space.core.model_params import ModelMicroCfg
  from src.third_pkg.models import CellStructure
label_desc: Use image node_id 1 to create a new ExponentialMovingAverage object from inherited base classes: object with example: obj = ExponentialMovingAverage(momentum)