text: from typing import Optional
  
  # moving average class
  class MovAvg:
  
      def __init__(self, factor=0.1):
          self.value: Optional[float] = None
          self.factor = factor
  
      def upd(self, val: float):
          if self.value is None: self.value = val
          else: self.value = (1-self.factor)*self.value + self.factor*val
          return self.value
  
      def __call__(self) -> float: return self.value