code: def _path_to_str(self, path):
          
          inp = ''
          for arc in path:
              i = self.isyms.find(arc.ilabel)
              # Ignore \epsilon transitions both on input
              if i != fst.EPSILON:
                  inp += i
          return inp
docs: Convert a path to the string representing the path
          Args:
              path (tuple): A tuple of arcs
          Returns:
              inp (str): The path concatenated as as string