code: def t_split(self):
      if self.y_prev is not None:
          return pd.to_datetime(self.y_prev.tf, unit="s")
      if self.yhat_prev is not None:
          return pd.to_datetime(self.yhat_prev.tf, unit="s")
      return None
  
imports: import logging
  from typing import Dict
  from copy import copy
  from matplotlib.colors import to_rgb
  from matplotlib.dates import AutoDateLocator, AutoDateFormatter
  import matplotlib.pyplot
  import numpy
  import pandas
  import plotly
  import plotly.graph_objects
  from plotly.subplots import make_subplots
  from merlion.utils import TimeSeries, UnivariateTimeSeries
label_desc: Use image node_id 4 for calling the MTSFigure obj's underlying member method code with example usage: obj.t_split() and returns: None, pd, pd