Create a generate that iterates the whole content of the file or string, starting from *begin* index,
        end by *end* index. **Not byte!**

        :param begin: An integer labels the starting index.
        :param end: An integer labels the ending index.
        :return: An iterator of string.

def generator_between(self, begin: int, end: int) -> Iterator[str]:
        """
        Create a generate that iterates the whole content of the file or string, starting from *begin* index,
        end by *end* index. **Not byte!**

        :param begin: An integer labels the starting index.
        :param end: An integer labels the ending index.
        :return: An iterator of string.
        """

        s: str = self.content[begin:end + 1]
        for line in s:
            yield line