class_docstr: Block with Granger causality matrix
class_docstr_tok: ["Block","with","Granger","causality","matrix"]
code: def _init_post(self) -> None:
      frame = self.result.result.frame
      self.dfp, self.dfl, self.granger_diff = frame.get(
          "granger_causality", (pd.DataFrame(), pd.DataFrame(), None)
      )
  
imports: from typing import List, Tuple, Callable, Any
  import pandas
  from tslumen.plot import interactive
  from tslumen.plot.interactive.base import go
  from tslumen.report.dashboard._dash import dbc, html, Component, Plot, EmptyFigure
  from tslumen.report.dashboard.base import DashInput, DashSection, DashBlock
label_desc: Use image node_id 1 for calling the BlockTSGranger obj's underlying member method code with example usage: obj._init_post() without return types