code: def save_model(self, fname, include_unsigned_edges=False):
          
          sif_str = self.print_model(include_unsigned_edges)
          with open(fname, 'wb') as fh:
              fh.write(sif_str.encode('utf-8'))
docs: Save the assembled model's SIF string into a file.
  
          Parameters
          ----------
          fname : str
              The name of the file to save the SIF into.
          include_unsigned_edges : bool
              If True, includes edges with an unknown activating/inactivating
              relationship (e.g., most PTMs). Default is False.