code: def _slice_idxs(df, twin=None):
      
      if twin is None:
          return 0, df.shape[0]
  
      tme = df.index
  
      if twin[0] is None:
          st_idx = 0
      else:
          st_idx = (np.abs(tme - twin[0])).argmin()
      if twin[1] is None:
          en_idx = df.shape[0]
      else:
          en_idx = (np.abs(tme - twin[1])).argmin() + 1
      return st_idx, en_idx
docs: Returns a slice of the incoming array filtered between
      the two times specified. Assumes the array is the same
      length as self.data. Acts in the time() and trace() functions.