code: def get_epoch_start(self, window_start):
          
          epoch_starts = [x['start'] for x in self.epochs]
          idx = asarray([abs(window_start - x) for x in epoch_starts]).argmin()
  
          return epoch_starts[idx]
docs: Get the position (seconds) of the nearest epoch.
  
          Parameters
          ----------
          window_start : float
              Position of the current window (seconds)
  
          Returns
          -------
          float
              Position (seconds) of the nearest epoch.