class_docstr: maintains an exponential moving average
code: def num_updates(self):
      return len(self.f_ma)
  
file_path: nni/nni/algorithms/feature_engineering/gradient_selector/utils.py
imports: import numpy
label_desc: Use image node_id 5 for calling the EMA obj's underlying member method code with example usage: obj.num_updates() and returns: len