class_docstr: maintains an exponential moving average
code: def reset(self, f):
      self.f_ma = [f]
      self.fs = [f]
      self.rel_change = [np.nan]
      self.initialized = True
  
file_path: nni/nni/algorithms/feature_engineering/gradient_selector/utils.py
imports: import numpy
label_desc: Use image node_id 2 for calling the EMA obj's underlying member method code with example usage: obj.reset(f) without return types