code: def get_scissors_builder(self):
          
          from abipy.electrons.scissors import ScissorsBuilder
          if self.sigres_path:
              return ScissorsBuilder.from_file(self.sigres_path)
          else:
              raise RuntimeError("Cannot find SIGRES file!")
docs: Returns an instance of :class:`ScissorsBuilder` from the SIGRES file.
  
          Raise:
              `RuntimeError` if SIGRES file is not found.