Better error message for improperly formatted dictionaries

                        return cls.load(fd)

            except FileNotFoundError as fnfe:

                raise fnfe

            except Exception:

            except UnicodeError:

                raise Exception("Incorrect encoding detected in {}, please "

                                "rebuild the dataset".format(f))

        d = cls()

        for line in f.readlines():

            idx = line.rfind(' ')

            if idx == -1:

                raise ValueError("Incorrect dictionary format, expected '<token> <cnt>'")

            word = line[:idx]

            count = int(line[idx+1:])

            d.indices[word] = len(d.symbols)