docs: def _load_script(self):
          """Loads the script from the filesystem
  
          :raises exceptions.IOError: if the script file could not be opened
          """
          script_text = filesystem.read_file(self.path, self.filename)
  
          if not script_text:
              raise IOError("Script file could not be opened or was empty: {0}"
                            "".format(os.path.join(self.path, self.filename)))
          self.script = script_text