code: def spia_matrices_to_excel(spia_matrices: Mapping[str, pd.DataFrame], path: str) -> None:
      
      writer = pd.ExcelWriter(path, engine='xlsxwriter')
  
      for relation, df in spia_matrices.items():
          df.to_excel(writer, sheet_name=relation, index=False)
  
      # Save excel
      writer.save()
docs: Export a SPIA data dictionary into an Excel sheet at the given path.
  
      .. note::
  
          # The R import should add the values:
          # ["nodes"] from the columns
          # ["title"] from the name of the file
          # ["NumberOfReactions"] set to "0"